diff --git a/gtk/actions.cc b/gtk/Actions.cc
similarity index 98%
rename from gtk/actions.cc
rename to gtk/Actions.cc
index e8676de0a..15a6b81c7 100644
--- a/gtk/actions.cc
+++ b/gtk/Actions.cc
@@ -15,16 +15,16 @@
 
 #include <libtransmission/transmission.h>
 
-#include "actions.h"
-#include "conf.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "Actions.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 namespace
 {
 
-TrCore* myCore = nullptr;
+Session* myCore = nullptr;
 
 void action_cb(Glib::RefPtr<Gtk::Action> const& a, void* user_data)
 {
@@ -176,7 +176,7 @@ Gtk::UIManager* myUIManager = nullptr;
 
 } // namespace
 
-void gtr_actions_set_core(Glib::RefPtr<TrCore> const& core)
+void gtr_actions_set_core(Glib::RefPtr<Session> const& core)
 {
     myCore = gtr_get_ptr(core);
 }
diff --git a/gtk/actions.h b/gtk/Actions.h
similarity index 92%
rename from gtk/actions.h
rename to gtk/Actions.h
index 8f52df25f..b347df1ce 100644
--- a/gtk/actions.h
+++ b/gtk/Actions.h
@@ -10,14 +10,14 @@
 
 #include <gtkmm.h>
 
-#include "tr-core.h"
+class Session;
 
 #define WINDOW_ICON "transmission-main-window-icon"
 #define TRAY_ICON "transmission-tray-icon"
 #define NOTIFICATION_ICON "transmission-notification-icon"
 
 void gtr_actions_init(Glib::RefPtr<Gtk::UIManager> const& ui_manager, void* callback_user_data);
-void gtr_actions_set_core(Glib::RefPtr<TrCore> const& core);
+void gtr_actions_set_core(Glib::RefPtr<Session> const& core);
 void gtr_actions_handler(Glib::ustring const& action_name, void* user_data);
 
 void gtr_action_activate(Glib::ustring const& action_name);
diff --git a/gtk/application.cc b/gtk/Application.cc
similarity index 98%
rename from gtk/application.cc
rename to gtk/Application.cc
index e4a3227db..7f94641ed 100644
--- a/gtk/application.cc
+++ b/gtk/Application.cc
@@ -40,22 +40,22 @@
 #include <libtransmission/utils.h>
 #include <libtransmission/version.h>
 
-#include "actions.h"
-#include "application.h"
-#include "conf.h"
-#include "details.h"
-#include "dialogs.h"
-#include "hig.h"
-#include "makemeta-ui.h"
-#include "msgwin.h"
-#include "open-dialog.h"
-#include "relocate.h"
-#include "stats.h"
-#include "tr-core.h"
-#include "tr-icon.h"
-#include "tr-prefs.h"
-#include "tr-window.h"
-#include "util.h"
+#include "Actions.h"
+#include "Application.h"
+#include "DetailsDialog.h"
+#include "Dialogs.h"
+#include "HigWorkarea.h"
+#include "MainWindow.h"
+#include "MakeDialog.h"
+#include "MessageLogWindow.h"
+#include "OptionsDialog.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "RelocateDialog.h"
+#include "Session.h"
+#include "StatsDialog.h"
+#include "SystemTrayIcon.h"
+#include "Utils.h"
 
 #define MY_CONFIG_NAME "transmission"
 
@@ -145,7 +145,7 @@ private:
     bool update_model_loop();
 
     void on_core_busy(bool busy);
-    void on_core_error(TrCore::ErrorCode code, Glib::ustring const& msg);
+    void on_core_error(Session::ErrorCode code, Glib::ustring const& msg);
     void on_add_torrent(tr_ctor* ctor);
     void on_prefs_changed(tr_quark key);
 
@@ -179,7 +179,7 @@ private:
     sigc::connection refresh_actions_tag_;
     std::unique_ptr<SystemTrayIcon> icon_;
     std::unique_ptr<MainWindow> wind_;
-    Glib::RefPtr<TrCore> core_;
+    Glib::RefPtr<Session> core_;
     std::unique_ptr<MessageLogWindow> msgwin_;
     std::unique_ptr<PrefsDialog> prefs_;
     std::vector<std::string> error_list_;
@@ -557,7 +557,7 @@ void Application::Impl::on_startup()
 
     gtr_pref_flag_set(TR_KEY_alt_speed_enabled, tr_sessionUsesAltSpeed(session));
     gtr_pref_int_set(TR_KEY_peer_port, tr_sessionGetPeerPort(session));
-    core_ = TrCore::create(session);
+    core_ = Session::create(session);
 
     /* init the ui manager */
     ui_manager_ = Gtk::UIManager::create();
@@ -958,19 +958,19 @@ void Application::Impl::flush_torrent_errors()
     }
 }
 
-void Application::Impl::on_core_error(TrCore::ErrorCode code, Glib::ustring const& msg)
+void Application::Impl::on_core_error(Session::ErrorCode code, Glib::ustring const& msg)
 {
     switch (code)
     {
-    case TrCore::ERR_ADD_TORRENT_ERR:
+    case Session::ERR_ADD_TORRENT_ERR:
         error_list_.push_back(Glib::path_get_basename(msg));
         break;
 
-    case TrCore::ERR_ADD_TORRENT_DUP:
+    case Session::ERR_ADD_TORRENT_DUP:
         duplicates_list_.push_back(msg);
         break;
 
-    case TrCore::ERR_NO_MORE_TORRENTS:
+    case Session::ERR_NO_MORE_TORRENTS:
         flush_torrent_errors();
         break;
 
diff --git a/gtk/application.h b/gtk/Application.h
similarity index 100%
rename from gtk/application.h
rename to gtk/Application.h
diff --git a/gtk/CMakeLists.txt b/gtk/CMakeLists.txt
index 5ec4d7865..38aa9543d 100644
--- a/gtk/CMakeLists.txt
+++ b/gtk/CMakeLists.txt
@@ -68,55 +68,57 @@ if(ENABLE_NLS)
 endif()
 
 set(${PROJECT_NAME}_SOURCES
-    actions.cc
-    application.cc
-    conf.cc
-    details.cc
-    dialogs.cc
-    favicon.cc
-    file-list.cc
-    filter.cc
-    hig.cc
-    icons.cc
+    Actions.cc
+    Application.cc
+    DetailsDialog.cc
+    Dialogs.cc
+    FaviconCache.cc
+    FileList.cc
+    FilterBar.cc
+    FreeSpaceLabel.cc
+    HigWorkarea.cc
+    IconCache.cc
     main.cc
-    makemeta-ui.cc
-    msgwin.cc
-    notify.cc
-    open-dialog.cc
-    relocate.cc
-    stats.cc
-    torrent-cell-renderer.cc
-    tr-core.cc
-    tr-icon.cc
-    tr-prefs.cc
-    tr-window.cc
-    util.cc
+    MainWindow.cc
+    MakeDialog.cc
+    MessageLogWindow.cc
+    Notify.cc
+    OptionsDialog.cc
+    Prefs.cc
+    PrefsDialog.cc
+    RelocateDialog.cc
+    Session.cc
+    StatsDialog.cc
+    SystemTrayIcon.cc
+    TorrentCellRenderer.cc
+    Utils.cc
     ${CMAKE_CURRENT_BINARY_DIR}/transmission-resources.c
 )
 
 set(${PROJECT_NAME}_HEADERS
-    actions.h
-    application.h
-    conf.h
-    details.h
-    dialogs.h
-    favicon.h
-    file-list.h
-    filter.h
-    hig.h
-    icons.h
-    makemeta-ui.h
-    msgwin.h
-    notify.h
-    open-dialog.h
-    relocate.h
-    stats.h
-    torrent-cell-renderer.h
-    tr-core.h
-    tr-icon.h
-    tr-prefs.h
-    tr-window.h
-    util.h
+    Actions.h
+    Application.h
+    DetailsDialog.h
+    Dialogs.h
+    FaviconCache.h
+    FileList.h
+    FilterBar.h
+    FreeSpaceLabel.h
+    HigWorkarea.h
+    IconCache.h
+    MainWindow.h
+    MakeDialog.h
+    MessageLogWindow.h
+    Notify.h
+    OptionsDialog.h
+    Prefs.h
+    PrefsDialog.h
+    RelocateDialog.h
+    Session.h
+    StatsDialog.h
+    SystemTrayIcon.h
+    TorrentCellRenderer.h
+    Utils.h
     ${CMAKE_CURRENT_BINARY_DIR}/transmission-resources.h
 )
 
diff --git a/gtk/details.cc b/gtk/DetailsDialog.cc
similarity index 99%
rename from gtk/details.cc
rename to gtk/DetailsDialog.cc
index 372339984..01d976b69 100644
--- a/gtk/details.cc
+++ b/gtk/DetailsDialog.cc
@@ -20,22 +20,22 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h> /* tr_free */
 
-#include "actions.h"
-#include "conf.h"
-#include "details.h"
-#include "favicon.h" /* gtr_get_favicon() */
-#include "file-list.h"
-#include "hig.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "Actions.h"
+#include "DetailsDialog.h"
+#include "FaviconCache.h" /* gtr_get_favicon() */
+#include "FileList.h"
+#include "HigWorkarea.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 using namespace std::literals;
 
 class DetailsDialog::Impl
 {
 public:
-    Impl(DetailsDialog& dialog, Glib::RefPtr<TrCore> const& core);
+    Impl(DetailsDialog& dialog, Glib::RefPtr<Session> const& core);
     ~Impl();
 
     void set_torrents(std::vector<int> const& torrent_ids);
@@ -148,7 +148,7 @@ private:
     Gtk::Label* file_label_ = nullptr;
 
     std::vector<int> ids_;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     sigc::connection periodic_refresh_tag_;
 
     Glib::Quark const TORRENT_ID_KEY = Glib::Quark("tr-torrent-id-key");
@@ -2570,12 +2570,12 @@ DetailsDialog::Impl::~Impl()
     periodic_refresh_tag_.disconnect();
 }
 
-std::unique_ptr<DetailsDialog> DetailsDialog::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<DetailsDialog> DetailsDialog::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<DetailsDialog>(new DetailsDialog(parent, core));
 }
 
-DetailsDialog::DetailsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+DetailsDialog::DetailsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Dialog({}, parent)
     , impl_(std::make_unique<Impl>(*this, core))
 {
@@ -2583,7 +2583,7 @@ DetailsDialog::DetailsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& co
 
 DetailsDialog::~DetailsDialog() = default;
 
-DetailsDialog::Impl::Impl(DetailsDialog& dialog, Glib::RefPtr<TrCore> const& core)
+DetailsDialog::Impl::Impl(DetailsDialog& dialog, Glib::RefPtr<Session> const& core)
     : dialog_(dialog)
     , core_(core)
 {
diff --git a/gtk/details.h b/gtk/DetailsDialog.h
similarity index 80%
rename from gtk/details.h
rename to gtk/DetailsDialog.h
index 96606b871..b34f0e8d8 100644
--- a/gtk/details.h
+++ b/gtk/DetailsDialog.h
@@ -14,19 +14,19 @@
 #include <glibmm.h>
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class DetailsDialog : public Gtk::Dialog
 {
 public:
     ~DetailsDialog() override;
 
-    static std::unique_ptr<DetailsDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<DetailsDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
     void set_torrents(std::vector<int> const& torrent_ids);
 
 protected:
-    DetailsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    DetailsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/dialogs.cc b/gtk/Dialogs.cc
similarity index 97%
rename from gtk/dialogs.cc
rename to gtk/Dialogs.cc
index b1bd5399c..ea1bb2e7b 100644
--- a/gtk/dialogs.cc
+++ b/gtk/Dialogs.cc
@@ -27,9 +27,9 @@
 
 #include <libtransmission/transmission.h>
 
-#include "dialogs.h"
-#include "tr-core.h"
-#include "util.h"
+#include "Dialogs.h"
+#include "Session.h"
+#include "Utils.h"
 
 /***
 ****
@@ -37,7 +37,7 @@
 
 void gtr_confirm_remove(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::vector<int> const& torrent_ids,
     bool delete_files)
 {
diff --git a/gtk/dialogs.h b/gtk/Dialogs.h
similarity index 96%
rename from gtk/dialogs.h
rename to gtk/Dialogs.h
index 1b6a0d373..ea9d5af3f 100644
--- a/gtk/dialogs.h
+++ b/gtk/Dialogs.h
@@ -26,13 +26,13 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 /**
  * Prompt the user to confirm removing a torrent.
  */
 void gtr_confirm_remove(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::vector<int> const& torrent_ids,
     bool delete_files);
diff --git a/gtk/favicon.cc b/gtk/FaviconCache.cc
similarity index 98%
rename from gtk/favicon.cc
rename to gtk/FaviconCache.cc
index 594043f3a..8c01eb290 100644
--- a/gtk/favicon.cc
+++ b/gtk/FaviconCache.cc
@@ -13,8 +13,8 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/web.h> /* tr_webRun() */
 
-#include "favicon.h"
-#include "util.h" /* gtr_get_host_from_url() */
+#include "FaviconCache.h"
+#include "Utils.h" /* gtr_get_host_from_url() */
 
 namespace
 {
diff --git a/gtk/favicon.h b/gtk/FaviconCache.h
similarity index 100%
rename from gtk/favicon.h
rename to gtk/FaviconCache.h
diff --git a/gtk/file-list.cc b/gtk/FileList.cc
similarity index 98%
rename from gtk/file-list.cc
rename to gtk/FileList.cc
index b1e6c0f5b..2acd6ac00 100644
--- a/gtk/file-list.cc
+++ b/gtk/FileList.cc
@@ -17,12 +17,12 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h>
 
-#include "file-list.h"
-#include "hig.h"
-#include "icons.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "FileList.h"
+#include "HigWorkarea.h"
+#include "IconCache.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 #define TR_COLUMN_ID_KEY "tr-model-column-id-key"
 
@@ -73,7 +73,7 @@ FileModelColumns const file_cols;
 class FileList::Impl
 {
 public:
-    Impl(FileList& widget, Glib::RefPtr<TrCore> const& core, int torrent_id);
+    Impl(FileList& widget, Glib::RefPtr<Session> const& core, int torrent_id);
     ~Impl();
 
     void set_torrent(int torrent_id);
@@ -97,7 +97,7 @@ private:
 private:
     FileList& widget_;
 
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     // GtkWidget* top_ = nullptr; // == widget_
     Gtk::TreeView* view_ = nullptr;
     Glib::RefPtr<Gtk::TreeStore> store_;
@@ -815,13 +815,13 @@ void FileList::Impl::cell_edited_callback(Glib::ustring const& path_string, Glib
         rename_data);
 }
 
-FileList::FileList(Glib::RefPtr<TrCore> const& core, int torrent_id)
+FileList::FileList(Glib::RefPtr<Session> const& core, int torrent_id)
     : Gtk::ScrolledWindow()
     , impl_(std::make_unique<Impl>(*this, core, torrent_id))
 {
 }
 
-FileList::Impl::Impl(FileList& widget, Glib::RefPtr<TrCore> const& core, int torrent_id)
+FileList::Impl::Impl(FileList& widget, Glib::RefPtr<Session> const& core, int torrent_id)
     : widget_(widget)
     , core_(core)
 {
diff --git a/gtk/file-list.h b/gtk/FileList.h
similarity index 84%
rename from gtk/file-list.h
rename to gtk/FileList.h
index 19dd62646..f5423b8f2 100644
--- a/gtk/file-list.h
+++ b/gtk/FileList.h
@@ -12,12 +12,12 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class FileList : public Gtk::ScrolledWindow
 {
 public:
-    FileList(Glib::RefPtr<TrCore> const& core, int torrent_id);
+    FileList(Glib::RefPtr<Session> const& core, int torrent_id);
     ~FileList() override;
 
     void clear();
diff --git a/gtk/filter.cc b/gtk/FilterBar.cc
similarity index 99%
rename from gtk/filter.cc
rename to gtk/FilterBar.cc
index 0dcd16fcd..a1d8d5dd3 100644
--- a/gtk/filter.cc
+++ b/gtk/FilterBar.cc
@@ -16,11 +16,11 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h>
 
-#include "favicon.h" /* gtr_get_favicon() */
-#include "filter.h"
-#include "hig.h" /* GUI_PAD */
-#include "tr-core.h" /* MC_TORRENT */
-#include "util.h" /* gtr_get_host_from_url() */
+#include "FaviconCache.h" /* gtr_get_favicon() */
+#include "FilterBar.h"
+#include "HigWorkarea.h" /* GUI_PAD */
+#include "Session.h" /* MC_TORRENT */
+#include "Utils.h" /* gtr_get_host_from_url() */
 
 namespace
 {
diff --git a/gtk/filter.h b/gtk/FilterBar.h
similarity index 100%
rename from gtk/filter.h
rename to gtk/FilterBar.h
diff --git a/gtk/FreeSpaceLabel.cc b/gtk/FreeSpaceLabel.cc
new file mode 100644
index 000000000..a5261958d
--- /dev/null
+++ b/gtk/FreeSpaceLabel.cc
@@ -0,0 +1,80 @@
+/*
+ * This file Copyright (C) 2008-2021 Mnemosyne LLC
+ *
+ * It may be used under the GNU GPL versions 2 or 3
+ * or any future license endorsed by Mnemosyne LLC.
+ *
+ */
+
+#include <glibmm/i18n.h>
+
+#include "FreeSpaceLabel.h"
+#include "Session.h"
+#include "Utils.h"
+
+class FreeSpaceLabel::Impl
+{
+public:
+    Impl(FreeSpaceLabel& label, Glib::RefPtr<Session> const& core, std::string const& dir);
+    ~Impl();
+
+    void set_dir(std::string const& dir);
+
+private:
+    bool on_freespace_timer();
+
+private:
+    FreeSpaceLabel& label_;
+    Glib::RefPtr<Session> const core_;
+    std::string dir_;
+    sigc::connection timer_id_;
+};
+
+FreeSpaceLabel::Impl::~Impl()
+{
+    timer_id_.disconnect();
+}
+
+bool FreeSpaceLabel::Impl::on_freespace_timer()
+{
+    auto* const session = core_->get_session();
+    if (session == nullptr)
+    {
+        return false;
+    }
+
+    auto const bytes = tr_sessionGetDirFreeSpace(session, dir_.c_str());
+    auto const text = bytes < 0 ? _("Error") : gtr_sprintf(_("%s free"), tr_strlsize(bytes));
+    auto const markup = gtr_sprintf("<i>%s</i>", text);
+    label_.set_markup(markup);
+
+    return true;
+}
+
+FreeSpaceLabel::FreeSpaceLabel(Glib::RefPtr<Session> const& core, std::string const& dir)
+    : Gtk::Label()
+    , impl_(std::make_unique<Impl>(*this, core, dir))
+{
+}
+
+FreeSpaceLabel::~FreeSpaceLabel() = default;
+
+FreeSpaceLabel::Impl::Impl(FreeSpaceLabel& label, Glib::RefPtr<Session> const& core, std::string const& dir)
+    : label_(label)
+    , core_(core)
+    , dir_(dir)
+{
+    timer_id_ = Glib::signal_timeout().connect_seconds(sigc::mem_fun(this, &Impl::on_freespace_timer), 3);
+    on_freespace_timer();
+}
+
+void FreeSpaceLabel::set_dir(std::string const& dir)
+{
+    impl_->set_dir(dir);
+}
+
+void FreeSpaceLabel::Impl::set_dir(std::string const& dir)
+{
+    dir_ = dir;
+    on_freespace_timer();
+}
diff --git a/gtk/FreeSpaceLabel.h b/gtk/FreeSpaceLabel.h
new file mode 100644
index 000000000..5f4d78ad7
--- /dev/null
+++ b/gtk/FreeSpaceLabel.h
@@ -0,0 +1,28 @@
+/*
+ * This file Copyright (C) 2008-2021 Mnemosyne LLC
+ *
+ * It may be used under the GNU GPL versions 2 or 3
+ * or any future license endorsed by Mnemosyne LLC.
+ *
+ */
+
+#include <memory>
+#include <string>
+
+#include <glibmm.h>
+#include <gtkmm.h>
+
+class Session;
+
+class FreeSpaceLabel : public Gtk::Label
+{
+public:
+    FreeSpaceLabel(Glib::RefPtr<Session> const& core, std::string const& dir = {});
+    ~FreeSpaceLabel() override;
+
+    void set_dir(std::string const& dir);
+
+private:
+    class Impl;
+    std::unique_ptr<Impl> const impl_;
+};
diff --git a/gtk/hig.cc b/gtk/HigWorkarea.cc
similarity index 98%
rename from gtk/hig.cc
rename to gtk/HigWorkarea.cc
index 5eef6852b..723e114ac 100644
--- a/gtk/hig.cc
+++ b/gtk/HigWorkarea.cc
@@ -8,8 +8,8 @@
 
 #include <libtransmission/tr-macros.h>
 
-#include "hig.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "Utils.h"
 
 HigWorkarea::HigWorkarea()
 {
diff --git a/gtk/hig.h b/gtk/HigWorkarea.h
similarity index 100%
rename from gtk/hig.h
rename to gtk/HigWorkarea.h
diff --git a/gtk/icons.cc b/gtk/IconCache.cc
similarity index 99%
rename from gtk/icons.cc
rename to gtk/IconCache.cc
index 76896a65b..f2725462e 100644
--- a/gtk/icons.cc
+++ b/gtk/IconCache.cc
@@ -11,8 +11,8 @@
 #include <glibmm.h>
 #include <giomm.h>
 
-#include "icons.h"
-#include "util.h"
+#include "IconCache.h"
+#include "Utils.h"
 
 #define VOID_PIXBUF_KEY "void-pixbuf"
 
diff --git a/gtk/icons.h b/gtk/IconCache.h
similarity index 100%
rename from gtk/icons.h
rename to gtk/IconCache.h
diff --git a/gtk/tr-window.cc b/gtk/MainWindow.cc
similarity index 98%
rename from gtk/tr-window.cc
rename to gtk/MainWindow.cc
index d61f0e792..75f3aa82d 100644
--- a/gtk/tr-window.cc
+++ b/gtk/MainWindow.cc
@@ -27,20 +27,20 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h> /* tr_formatter_speed_KBps() */
 
-#include "actions.h"
-#include "conf.h"
-#include "filter.h"
-#include "hig.h"
-#include "torrent-cell-renderer.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "tr-window.h"
-#include "util.h"
+#include "Actions.h"
+#include "FilterBar.h"
+#include "HigWorkarea.h"
+#include "MainWindow.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "TorrentCellRenderer.h"
+#include "Utils.h"
 
 class MainWindow::Impl
 {
 public:
-    Impl(MainWindow& window, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<TrCore> const& core);
+    Impl(MainWindow& window, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<Session> const& core);
     ~Impl();
 
     Glib::RefPtr<Gtk::TreeSelection> get_selection() const;
@@ -94,7 +94,7 @@ private:
     Glib::RefPtr<Gtk::TreeSelection> selection_;
     TorrentCellRenderer* renderer_ = nullptr;
     Gtk::TreeViewColumn* column_ = nullptr;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     sigc::connection pref_handler_id_;
 };
 
@@ -449,12 +449,12 @@ void MainWindow::Impl::onOptionsClicked(Gtk::Button* button)
 std::unique_ptr<MainWindow> MainWindow::create(
     Gtk::Application& app,
     Glib::RefPtr<Gtk::UIManager> const& uim,
-    Glib::RefPtr<TrCore> const& core)
+    Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<MainWindow>(new MainWindow(app, uim, core));
 }
 
-MainWindow::MainWindow(Gtk::Application& app, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<TrCore> const& core)
+MainWindow::MainWindow(Gtk::Application& app, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<Session> const& core)
     : Gtk::ApplicationWindow()
     , impl_(std::make_unique<Impl>(*this, ui_mgr, core))
 {
@@ -463,7 +463,7 @@ MainWindow::MainWindow(Gtk::Application& app, Glib::RefPtr<Gtk::UIManager> const
 
 MainWindow::~MainWindow() = default;
 
-MainWindow::Impl::Impl(MainWindow& window, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<TrCore> const& core)
+MainWindow::Impl::Impl(MainWindow& window, Glib::RefPtr<Gtk::UIManager> const& ui_mgr, Glib::RefPtr<Session> const& core)
     : core_(core)
 {
     static struct
diff --git a/gtk/tr-window.h b/gtk/MainWindow.h
similarity index 94%
rename from gtk/tr-window.h
rename to gtk/MainWindow.h
index 808167342..26ef9fd70 100644
--- a/gtk/tr-window.h
+++ b/gtk/MainWindow.h
@@ -27,7 +27,7 @@
 #include <glibmm.h>
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class MainWindow : public Gtk::ApplicationWindow
 {
@@ -37,7 +37,7 @@ public:
     static std::unique_ptr<MainWindow> create(
         Gtk::Application& app,
         Glib::RefPtr<Gtk::UIManager> const& uim,
-        Glib::RefPtr<TrCore> const& core);
+        Glib::RefPtr<Session> const& core);
 
     Glib::RefPtr<Gtk::TreeSelection> get_selection() const;
 
@@ -45,7 +45,7 @@ public:
     void refresh();
 
 protected:
-    MainWindow(Gtk::Application& app, Glib::RefPtr<Gtk::UIManager> const& uim, Glib::RefPtr<TrCore> const& core);
+    MainWindow(Gtk::Application& app, Glib::RefPtr<Gtk::UIManager> const& uim, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/makemeta-ui.cc b/gtk/MakeDialog.cc
similarity index 96%
rename from gtk/makemeta-ui.cc
rename to gtk/MakeDialog.cc
index 9d8b1d1a7..991efb6ed 100644
--- a/gtk/makemeta-ui.cc
+++ b/gtk/MakeDialog.cc
@@ -13,11 +13,11 @@
 #include <libtransmission/makemeta.h>
 #include <libtransmission/utils.h> /* tr_formatter_mem_B() */
 
-#include "hig.h"
-#include "makemeta-ui.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "MakeDialog.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 #define FILE_CHOSEN_KEY "file-is-chosen"
 
@@ -31,7 +31,7 @@ public:
         Gtk::Window& parent,
         tr_metainfo_builder& builder,
         std::string const& target,
-        Glib::RefPtr<TrCore> const& core);
+        Glib::RefPtr<Session> const& core);
     ~MakeProgressDialog() override;
 
 private:
@@ -43,7 +43,7 @@ private:
 private:
     tr_metainfo_builder& builder_;
     std::string const target_;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
 
     sigc::connection progress_tag_;
     Gtk::Label* progress_label_ = nullptr;
@@ -55,7 +55,7 @@ private:
 class MakeDialog::Impl
 {
 public:
-    Impl(MakeDialog& dialog, Glib::RefPtr<TrCore> const& core);
+    Impl(MakeDialog& dialog, Glib::RefPtr<Session> const& core);
 
 private:
     void onSourceToggled2(Gtk::ToggleButton* tb, Gtk::FileChooserButton* chooser);
@@ -78,7 +78,7 @@ private:
 
 private:
     MakeDialog& dialog_;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
 
     Gtk::RadioButton* file_radio_ = nullptr;
     Gtk::FileChooserButton* file_chooser_ = nullptr;
@@ -195,7 +195,7 @@ MakeProgressDialog::MakeProgressDialog(
     Gtk::Window& parent,
     tr_metainfo_builder& builder,
     std::string const& target,
-    Glib::RefPtr<TrCore> const& core)
+    Glib::RefPtr<Session> const& core)
     : Gtk::Dialog(_("New Torrent"), parent, true)
     , builder_(builder)
     , target_(target)
@@ -415,12 +415,12 @@ void MakeDialog::Impl::on_drag_data_received(
     drag_context->drag_finish(success, false, time_);
 }
 
-std::unique_ptr<MakeDialog> MakeDialog::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<MakeDialog> MakeDialog::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<MakeDialog>(new MakeDialog(parent, core));
 }
 
-MakeDialog::MakeDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+MakeDialog::MakeDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Dialog(_("New Torrent"), parent)
     , impl_(std::make_unique<Impl>(*this, core))
 {
@@ -428,7 +428,7 @@ MakeDialog::MakeDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
 
 MakeDialog::~MakeDialog() = default;
 
-MakeDialog::Impl::Impl(MakeDialog& dialog, Glib::RefPtr<TrCore> const& core)
+MakeDialog::Impl::Impl(MakeDialog& dialog, Glib::RefPtr<Session> const& core)
     : dialog_(dialog)
     , core_(core)
 {
diff --git a/gtk/makemeta-ui.h b/gtk/MakeDialog.h
similarity index 77%
rename from gtk/makemeta-ui.h
rename to gtk/MakeDialog.h
index 526b97a90..1021ff375 100644
--- a/gtk/makemeta-ui.h
+++ b/gtk/MakeDialog.h
@@ -12,17 +12,17 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class MakeDialog : public Gtk::Dialog
 {
 public:
     ~MakeDialog() override;
 
-    static std::unique_ptr<MakeDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<MakeDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    MakeDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    MakeDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/msgwin.cc b/gtk/MessageLogWindow.cc
similarity index 97%
rename from gtk/msgwin.cc
rename to gtk/MessageLogWindow.cc
index db745dd3b..a5824108b 100644
--- a/gtk/msgwin.cc
+++ b/gtk/MessageLogWindow.cc
@@ -16,12 +16,12 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/log.h>
 
-#include "conf.h"
-#include "hig.h"
-#include "msgwin.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "MessageLogWindow.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 class MessageLogColumnsModel : public Gtk::TreeModelColumnRecord
 {
@@ -45,7 +45,7 @@ MessageLogColumnsModel const message_log_cols;
 class MessageLogWindow::Impl
 {
 public:
-    Impl(MessageLogWindow& window, Glib::RefPtr<TrCore> const& core);
+    Impl(MessageLogWindow& window, Glib::RefPtr<Session> const& core);
     ~Impl();
 
 private:
@@ -67,7 +67,7 @@ private:
 private:
     MessageLogWindow& window_;
 
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     Gtk::TreeView* view_ = nullptr;
     Glib::RefPtr<Gtk::ListStore> store_;
     Glib::RefPtr<Gtk::TreeModelFilter> filter_;
@@ -429,12 +429,12 @@ Gtk::ComboBox* debug_level_combo_new()
 ***  Public Functions
 **/
 
-std::unique_ptr<MessageLogWindow> MessageLogWindow::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<MessageLogWindow> MessageLogWindow::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<MessageLogWindow>(new MessageLogWindow(parent, core));
 }
 
-MessageLogWindow::MessageLogWindow(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+MessageLogWindow::MessageLogWindow(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Window(Gtk::WINDOW_TOPLEVEL)
     , impl_(std::make_unique<Impl>(*this, core))
 {
@@ -443,7 +443,7 @@ MessageLogWindow::MessageLogWindow(Gtk::Window& parent, Glib::RefPtr<TrCore> con
 
 MessageLogWindow::~MessageLogWindow() = default;
 
-MessageLogWindow::Impl::Impl(MessageLogWindow& window, Glib::RefPtr<TrCore> const& core)
+MessageLogWindow::Impl::Impl(MessageLogWindow& window, Glib::RefPtr<Session> const& core)
     : window_(window)
     , core_(core)
 {
diff --git a/gtk/msgwin.h b/gtk/MessageLogWindow.h
similarity index 76%
rename from gtk/msgwin.h
rename to gtk/MessageLogWindow.h
index ee6e23254..26f493683 100644
--- a/gtk/msgwin.h
+++ b/gtk/MessageLogWindow.h
@@ -12,17 +12,17 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class MessageLogWindow : public Gtk::Window
 {
 public:
     ~MessageLogWindow() override;
 
-    static std::unique_ptr<MessageLogWindow> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<MessageLogWindow> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    MessageLogWindow(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    MessageLogWindow(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/notify.cc b/gtk/Notify.cc
similarity index 96%
rename from gtk/notify.cc
rename to gtk/Notify.cc
index 8c509360a..737063e43 100644
--- a/gtk/notify.cc
+++ b/gtk/Notify.cc
@@ -11,11 +11,11 @@
 #include <giomm.h>
 #include <glibmm/i18n.h>
 
-#include "conf.h"
-#include "notify.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "Notify.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 #define NOTIFICATIONS_DBUS_NAME "org.freedesktop.Notifications"
 #define NOTIFICATIONS_DBUS_CORE_OBJECT "/org/freedesktop/Notifications"
@@ -30,7 +30,7 @@ namespace
 
 struct TrNotification
 {
-    Glib::RefPtr<TrCore> core;
+    Glib::RefPtr<Session> core;
     int torrent_id = 0;
 };
 
@@ -160,7 +160,7 @@ void notify_callback(Glib::RefPtr<Gio::AsyncResult>& res, TrNotification const&
 
 } // namespace
 
-void gtr_notify_torrent_completed(Glib::RefPtr<TrCore> const& core, int torrent_id)
+void gtr_notify_torrent_completed(Glib::RefPtr<Session> const& core, int torrent_id)
 {
     if (gtr_pref_flag_get(TR_KEY_torrent_complete_sound_enabled))
     {
diff --git a/gtk/notify.h b/gtk/Notify.h
similarity index 74%
rename from gtk/notify.h
rename to gtk/Notify.h
index 948385475..6e06f09ff 100644
--- a/gtk/notify.h
+++ b/gtk/Notify.h
@@ -10,10 +10,10 @@
 
 #include <glibmm.h>
 
-class TrCore;
+class Session;
 
 void gtr_notify_init();
 
 void gtr_notify_torrent_added(Glib::ustring const& name);
 
-void gtr_notify_torrent_completed(Glib::RefPtr<TrCore> const& core, int torrent_id);
+void gtr_notify_torrent_completed(Glib::RefPtr<Session> const& core, int torrent_id);
diff --git a/gtk/open-dialog.cc b/gtk/OptionsDialog.cc
similarity index 94%
rename from gtk/open-dialog.cc
rename to gtk/OptionsDialog.cc
index 31d93902a..12a2e06dd 100644
--- a/gtk/open-dialog.cc
+++ b/gtk/OptionsDialog.cc
@@ -15,13 +15,14 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/file.h> /* tr_sys_path_is_same() */
 
-#include "conf.h"
-#include "file-list.h"
-#include "hig.h"
-#include "open-dialog.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h" /* gtr_priority_combo_get_value() */
+#include "FileList.h"
+#include "FreeSpaceLabel.h"
+#include "HigWorkarea.h"
+#include "OptionsDialog.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h" /* gtr_priority_combo_get_value() */
 
 /****
 *****
@@ -49,7 +50,7 @@ std::list<std::string> get_recent_destinations()
     return list;
 }
 
-void save_recent_destination(Glib::RefPtr<TrCore> const& core, std::string const& dir)
+void save_recent_destination(Glib::RefPtr<Session> const& core, std::string const& dir)
 {
     if (dir.empty())
     {
@@ -85,7 +86,7 @@ void save_recent_destination(Glib::RefPtr<TrCore> const& core, std::string const
 class OptionsDialog::Impl
 {
 public:
-    Impl(OptionsDialog& dialog, Glib::RefPtr<TrCore> const& core, std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor);
+    Impl(OptionsDialog& dialog, Glib::RefPtr<Session> const& core, std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor);
 
 private:
     void sourceChanged(Gtk::FileChooserButton* b);
@@ -99,7 +100,7 @@ private:
 private:
     OptionsDialog& dialog_;
 
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     FileList* file_list_ = nullptr;
     Gtk::CheckButton* run_check_ = nullptr;
     Gtk::CheckButton* trash_check_ = nullptr;
@@ -253,7 +254,7 @@ void addTorrentFilters(Gtk::FileChooser* chooser)
 
 std::unique_ptr<OptionsDialog> OptionsDialog::create(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor)
 {
     return std::unique_ptr<OptionsDialog>(new OptionsDialog(parent, core, std::move(ctor)));
@@ -261,7 +262,7 @@ std::unique_ptr<OptionsDialog> OptionsDialog::create(
 
 OptionsDialog::OptionsDialog(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor)
     : Gtk::Dialog(_("Torrent Options"), parent)
     , impl_(std::make_unique<Impl>(*this, core, std::move(ctor)))
@@ -272,7 +273,7 @@ OptionsDialog::~OptionsDialog() = default;
 
 OptionsDialog::Impl::Impl(
     OptionsDialog& dialog,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor)
     : dialog_(dialog)
     , core_(core)
@@ -410,7 +411,7 @@ OptionsDialog::Impl::Impl(
 *****
 ****/
 
-void TorrentFileChooserDialog::onOpenDialogResponse(int response, Glib::RefPtr<TrCore> const& core)
+void TorrentFileChooserDialog::onOpenDialogResponse(int response, Glib::RefPtr<Session> const& core)
 {
     /* remember this folder the next time we use this dialog */
     gtr_pref_string_set(TR_KEY_open_dialog_dir, get_current_folder());
@@ -431,12 +432,12 @@ void TorrentFileChooserDialog::onOpenDialogResponse(int response, Glib::RefPtr<T
 
 std::unique_ptr<TorrentFileChooserDialog> TorrentFileChooserDialog::create(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core)
+    Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<TorrentFileChooserDialog>(new TorrentFileChooserDialog(parent, core));
 }
 
-TorrentFileChooserDialog::TorrentFileChooserDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+TorrentFileChooserDialog::TorrentFileChooserDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::FileChooserDialog(parent, _("Open a Torrent"), Gtk::FILE_CHOOSER_ACTION_OPEN)
 {
     add_button(_("_Cancel"), Gtk::RESPONSE_CANCEL);
@@ -461,7 +462,7 @@ TorrentFileChooserDialog::TorrentFileChooserDialog(Gtk::Window& parent, Glib::Re
 ****
 ***/
 
-void TorrentUrlChooserDialog::onOpenURLResponse(int response, Glib::RefPtr<TrCore> const& core)
+void TorrentUrlChooserDialog::onOpenURLResponse(int response, Glib::RefPtr<Session> const& core)
 {
     bool handled = false;
 
@@ -491,12 +492,12 @@ void TorrentUrlChooserDialog::onOpenURLResponse(int response, Glib::RefPtr<TrCor
     }
 }
 
-std::unique_ptr<TorrentUrlChooserDialog> TorrentUrlChooserDialog::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<TorrentUrlChooserDialog> TorrentUrlChooserDialog::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<TorrentUrlChooserDialog>(new TorrentUrlChooserDialog(parent, core));
 }
 
-TorrentUrlChooserDialog::TorrentUrlChooserDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+TorrentUrlChooserDialog::TorrentUrlChooserDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Dialog(_("Open URL"), parent)
 {
     guint row;
diff --git a/gtk/open-dialog.h b/gtk/OptionsDialog.h
similarity index 58%
rename from gtk/open-dialog.h
rename to gtk/OptionsDialog.h
index 8ef787e89..a7f3db3a8 100644
--- a/gtk/open-dialog.h
+++ b/gtk/OptionsDialog.h
@@ -12,31 +12,31 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 typedef struct tr_ctor tr_ctor;
 
 class TorrentUrlChooserDialog : public Gtk::Dialog
 {
 public:
-    static std::unique_ptr<TorrentUrlChooserDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<TorrentUrlChooserDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    TorrentUrlChooserDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    TorrentUrlChooserDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
-    void onOpenURLResponse(int response, Glib::RefPtr<TrCore> const& core);
+    void onOpenURLResponse(int response, Glib::RefPtr<Session> const& core);
 };
 
 class TorrentFileChooserDialog : public Gtk::FileChooserDialog
 {
 public:
-    static std::unique_ptr<TorrentFileChooserDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<TorrentFileChooserDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    TorrentFileChooserDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    TorrentFileChooserDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
-    void onOpenDialogResponse(int response, Glib::RefPtr<TrCore> const& core);
+    void onOpenDialogResponse(int response, Glib::RefPtr<Session> const& core);
 };
 
 class OptionsDialog : public Gtk::Dialog
@@ -46,11 +46,11 @@ public:
 
     static std::unique_ptr<OptionsDialog> create(
         Gtk::Window& parent,
-        Glib::RefPtr<TrCore> const& core,
+        Glib::RefPtr<Session> const& core,
         std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor);
 
 protected:
-    OptionsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core, std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor);
+    OptionsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core, std::unique_ptr<tr_ctor, void (*)(tr_ctor*)> ctor);
 
 private:
     class Impl;
diff --git a/gtk/conf.cc b/gtk/Prefs.cc
similarity index 99%
rename from gtk/conf.cc
rename to gtk/Prefs.cc
index 034aa1d01..9030dd5bb 100644
--- a/gtk/conf.cc
+++ b/gtk/Prefs.cc
@@ -34,9 +34,9 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/variant.h>
 
-#include "conf.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Utils.h"
 
 #define MY_CONFIG_NAME "transmission"
 
diff --git a/gtk/conf.h b/gtk/Prefs.h
similarity index 100%
rename from gtk/conf.h
rename to gtk/Prefs.h
diff --git a/gtk/tr-prefs.cc b/gtk/PrefsDialog.cc
similarity index 96%
rename from gtk/tr-prefs.cc
rename to gtk/PrefsDialog.cc
index 8936f8952..45e5e0e7a 100644
--- a/gtk/tr-prefs.cc
+++ b/gtk/PrefsDialog.cc
@@ -18,11 +18,12 @@
 #include <libtransmission/utils.h>
 #include <libtransmission/version.h>
 
-#include "conf.h"
-#include "hig.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "FreeSpaceLabel.h"
+#include "HigWorkarea.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 /**
 ***
@@ -31,7 +32,7 @@
 class PrefsDialog::Impl
 {
 public:
-    Impl(PrefsDialog& dialog, Glib::RefPtr<TrCore> const& core);
+    Impl(PrefsDialog& dialog, Glib::RefPtr<Session> const& core);
     ~Impl();
 
 private:
@@ -50,7 +51,7 @@ private:
 private:
     PrefsDialog& dialog_;
 
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     sigc::connection core_prefs_tag_;
 
     FreeSpaceLabel* freespace_label_ = nullptr;
@@ -82,7 +83,7 @@ void PrefsDialog::Impl::response_cb(int response)
 namespace
 {
 
-Gtk::CheckButton* new_check_button(Glib::ustring const& mnemonic, tr_quark const key, Glib::RefPtr<TrCore> const& core)
+Gtk::CheckButton* new_check_button(Glib::ustring const& mnemonic, tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     auto* w = Gtk::make_managed<Gtk::CheckButton>(mnemonic, true);
     w->set_active(gtr_pref_flag_get(key));
@@ -92,7 +93,7 @@ Gtk::CheckButton* new_check_button(Glib::ustring const& mnemonic, tr_quark const
 
 #define IDLE_DATA "idle-data"
 
-bool spun_cb_idle(Gtk::SpinButton* spin, tr_quark const key, Glib::RefPtr<TrCore> const& core, bool isDouble)
+bool spun_cb_idle(Gtk::SpinButton* spin, tr_quark const key, Glib::RefPtr<Session> const& core, bool isDouble)
 {
     bool keep_waiting = true;
     auto* last_change = static_cast<Glib::Timer*>(spin->get_data(IDLE_DATA));
@@ -121,7 +122,7 @@ bool spun_cb_idle(Gtk::SpinButton* spin, tr_quark const key, Glib::RefPtr<TrCore
     return keep_waiting;
 }
 
-void spun_cb(Gtk::SpinButton* w, tr_quark const key, Glib::RefPtr<TrCore> const& core, bool isDouble)
+void spun_cb(Gtk::SpinButton* w, tr_quark const key, Glib::RefPtr<Session> const& core, bool isDouble)
 {
     /* user may be spinning through many values, so let's hold off
        for a moment to keep from flooding the core with changes */
@@ -138,7 +139,7 @@ void spun_cb(Gtk::SpinButton* w, tr_quark const key, Glib::RefPtr<TrCore> const&
     last_change->start();
 }
 
-Gtk::SpinButton* new_spin_button(tr_quark const key, Glib::RefPtr<TrCore> const& core, int low, int high, int step)
+Gtk::SpinButton* new_spin_button(tr_quark const key, Glib::RefPtr<Session> const& core, int low, int high, int step)
 {
     auto* w = Gtk::make_managed<Gtk::SpinButton>(Gtk::Adjustment::create(gtr_pref_int_get(key), low, high, step));
     w->set_digits(0);
@@ -148,7 +149,7 @@ Gtk::SpinButton* new_spin_button(tr_quark const key, Glib::RefPtr<TrCore> const&
 
 Gtk::SpinButton* new_spin_button_double(
     tr_quark const key,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     double low,
     double high,
     double step)
@@ -159,12 +160,12 @@ Gtk::SpinButton* new_spin_button_double(
     return w;
 }
 
-void entry_changed_cb(Gtk::Entry* w, tr_quark const key, Glib::RefPtr<TrCore> const& core)
+void entry_changed_cb(Gtk::Entry* w, tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     core->set_pref(key, w->get_text());
 }
 
-Gtk::Entry* new_entry(tr_quark const key, Glib::RefPtr<TrCore> const& core)
+Gtk::Entry* new_entry(tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     auto* w = Gtk::make_managed<Gtk::Entry>();
 
@@ -177,12 +178,12 @@ Gtk::Entry* new_entry(tr_quark const key, Glib::RefPtr<TrCore> const& core)
     return w;
 }
 
-void chosen_cb(Gtk::FileChooser* w, tr_quark const key, Glib::RefPtr<TrCore> const& core)
+void chosen_cb(Gtk::FileChooser* w, tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     core->set_pref(key, w->get_filename());
 }
 
-Gtk::FileChooserButton* new_path_chooser_button(tr_quark const key, Glib::RefPtr<TrCore> const& core)
+Gtk::FileChooserButton* new_path_chooser_button(tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     auto* w = Gtk::make_managed<Gtk::FileChooserButton>(Gtk::FILE_CHOOSER_ACTION_SELECT_FOLDER);
 
@@ -195,7 +196,7 @@ Gtk::FileChooserButton* new_path_chooser_button(tr_quark const key, Glib::RefPtr
     return w;
 }
 
-Gtk::FileChooserButton* new_file_chooser_button(tr_quark const key, Glib::RefPtr<TrCore> const& core)
+Gtk::FileChooserButton* new_file_chooser_button(tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     auto* w = Gtk::make_managed<Gtk::FileChooserButton>(Gtk::FILE_CHOOSER_ACTION_OPEN);
 
@@ -368,10 +369,10 @@ struct blocklist_data
     std::unique_ptr<Gtk::MessageDialog> updateBlocklistDialog;
     Gtk::Label* label = nullptr;
     Gtk::CheckButton* check = nullptr;
-    Glib::RefPtr<TrCore> core;
+    Glib::RefPtr<Session> core;
 };
 
-void updateBlocklistText(Gtk::Label* w, Glib::RefPtr<TrCore> const& core)
+void updateBlocklistText(Gtk::Label* w, Glib::RefPtr<Session> const& core)
 {
     int const n = tr_blocklistGetRuleCount(core->get_session());
     w->set_markup(
@@ -396,7 +397,7 @@ void onBlocklistUpdateResponse(std::shared_ptr<blocklist_data> const& data)
 }
 
 /* core says the blocklist was updated */
-void onBlocklistUpdated(Glib::RefPtr<TrCore> const& core, int n, blocklist_data* data)
+void onBlocklistUpdated(Glib::RefPtr<Session> const& core, int n, blocklist_data* data)
 {
     bool const success = n >= 0;
     int const count = n >= 0 ? n : tr_blocklistGetRuleCount(core->get_session());
@@ -432,12 +433,12 @@ void on_blocklist_url_changed(Gtk::Editable* e, Gtk::Button* button)
     button->set_sensitive(is_url_valid);
 }
 
-void onIntComboChanged(Gtk::ComboBox* combo_box, tr_quark const key, Glib::RefPtr<TrCore> const& core)
+void onIntComboChanged(Gtk::ComboBox* combo_box, tr_quark const key, Glib::RefPtr<Session> const& core)
 {
     core->set_pref(key, gtr_combo_box_get_active_enum(*combo_box));
 }
 
-Gtk::ComboBox* new_encryption_combo(Glib::RefPtr<TrCore> const& core, tr_quark const key)
+Gtk::ComboBox* new_encryption_combo(Glib::RefPtr<Session> const& core, tr_quark const key)
 {
     auto* w = gtr_combo_box_new_enum({
         { _("Allow encryption"), TR_CLEAR_PREFERRED },
@@ -543,7 +544,7 @@ Glib::RefPtr<Gtk::ListStore> whitelist_tree_model_new(std::string const& whiteli
 
 struct remote_page
 {
-    Glib::RefPtr<TrCore> core;
+    Glib::RefPtr<Session> core;
     Gtk::TreeView* view;
     Glib::RefPtr<Gtk::ListStore> store;
     Gtk::Button* remove_button;
@@ -760,7 +761,7 @@ void refreshSchedSensitivity(std::shared_ptr<BandwidthPage> const& p)
     }
 }
 
-Gtk::ComboBox* new_time_combo(Glib::RefPtr<TrCore> const& core, tr_quark const key)
+Gtk::ComboBox* new_time_combo(Glib::RefPtr<Session> const& core, tr_quark const key)
 {
     class TimeModelColumns : public Gtk::TreeModelColumnRecord
     {
@@ -806,7 +807,7 @@ Gtk::ComboBox* new_time_combo(Glib::RefPtr<TrCore> const& core, tr_quark const k
     return w;
 }
 
-Gtk::ComboBox* new_week_combo(Glib::RefPtr<TrCore> const& core, tr_quark const key)
+Gtk::ComboBox* new_week_combo(Glib::RefPtr<Session> const& core, tr_quark const key)
 {
     auto* w = gtr_combo_box_new_enum({
         { _("Every Day"), TR_SCHED_ALL },
@@ -919,7 +920,7 @@ struct network_page_data
 {
     ~network_page_data();
 
-    Glib::RefPtr<TrCore> core;
+    Glib::RefPtr<Session> core;
     Gtk::Label* portLabel = nullptr;
     Gtk::Button* portButton = nullptr;
     Gtk::SpinButton* portSpin = nullptr;
@@ -1074,12 +1075,12 @@ void PrefsDialog::Impl::on_core_prefs_changed(tr_quark const key)
     }
 }
 
-std::unique_ptr<PrefsDialog> PrefsDialog::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<PrefsDialog> PrefsDialog::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<PrefsDialog>(new PrefsDialog(parent, core));
 }
 
-PrefsDialog::PrefsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+PrefsDialog::PrefsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Dialog(_("Transmission Preferences"), parent)
     , impl_(std::make_unique<Impl>(*this, core))
 {
@@ -1087,7 +1088,7 @@ PrefsDialog::PrefsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
 
 PrefsDialog::~PrefsDialog() = default;
 
-PrefsDialog::Impl::Impl(PrefsDialog& dialog, Glib::RefPtr<TrCore> const& core)
+PrefsDialog::Impl::Impl(PrefsDialog& dialog, Glib::RefPtr<Session> const& core)
     : dialog_(dialog)
     , core_(core)
 {
diff --git a/gtk/tr-prefs.h b/gtk/PrefsDialog.h
similarity index 81%
rename from gtk/tr-prefs.h
rename to gtk/PrefsDialog.h
index 898620f14..c30a2547d 100644
--- a/gtk/tr-prefs.h
+++ b/gtk/PrefsDialog.h
@@ -12,17 +12,17 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class PrefsDialog : public Gtk::Dialog
 {
 public:
     ~PrefsDialog() override;
 
-    static std::unique_ptr<PrefsDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<PrefsDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    PrefsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    PrefsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/relocate.cc b/gtk/RelocateDialog.cc
similarity index 91%
rename from gtk/relocate.cc
rename to gtk/RelocateDialog.cc
index 16ef97365..ddd3fb401 100644
--- a/gtk/relocate.cc
+++ b/gtk/RelocateDialog.cc
@@ -13,11 +13,11 @@
 
 #include <libtransmission/transmission.h>
 
-#include "conf.h" /* gtr_pref_string_get */
-#include "hig.h"
-#include "relocate.h"
-#include "tr-core.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "Prefs.h" /* gtr_pref_string_get */
+#include "RelocateDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 namespace
 {
@@ -29,7 +29,7 @@ std::string previousLocation;
 class RelocateDialog::Impl
 {
 public:
-    Impl(RelocateDialog& dialog, Glib::RefPtr<TrCore> const& core, std::vector<int> const& torrent_ids);
+    Impl(RelocateDialog& dialog, Glib::RefPtr<Session> const& core, std::vector<int> const& torrent_ids);
     ~Impl();
 
 private:
@@ -40,7 +40,7 @@ private:
 
 private:
     RelocateDialog& dialog_;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
     std::vector<int> torrent_ids_;
 
     int done_ = 0;
@@ -135,13 +135,13 @@ void RelocateDialog::Impl::onResponse(int response)
 
 std::unique_ptr<RelocateDialog> RelocateDialog::create(
     Gtk::Window& parent,
-    Glib::RefPtr<TrCore> const& core,
+    Glib::RefPtr<Session> const& core,
     std::vector<int> const& torrent_ids)
 {
     return std::unique_ptr<RelocateDialog>(new RelocateDialog(parent, core, torrent_ids));
 }
 
-RelocateDialog::RelocateDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core, std::vector<int> const& torrent_ids)
+RelocateDialog::RelocateDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core, std::vector<int> const& torrent_ids)
     : Gtk::Dialog(_("Set Torrent Location"), parent, true)
     , impl_(std::make_unique<Impl>(*this, core, torrent_ids))
 {
@@ -149,7 +149,7 @@ RelocateDialog::RelocateDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const&
 
 RelocateDialog::~RelocateDialog() = default;
 
-RelocateDialog::Impl::Impl(RelocateDialog& dialog, Glib::RefPtr<TrCore> const& core, std::vector<int> const& torrent_ids)
+RelocateDialog::Impl::Impl(RelocateDialog& dialog, Glib::RefPtr<Session> const& core, std::vector<int> const& torrent_ids)
     : dialog_(dialog)
     , core_(core)
     , torrent_ids_(torrent_ids)
diff --git a/gtk/relocate.h b/gtk/RelocateDialog.h
similarity index 75%
rename from gtk/relocate.h
rename to gtk/RelocateDialog.h
index f30f69e29..623f1deb5 100644
--- a/gtk/relocate.h
+++ b/gtk/RelocateDialog.h
@@ -13,7 +13,7 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class RelocateDialog : public Gtk::Dialog
 {
@@ -22,11 +22,11 @@ public:
 
     static std::unique_ptr<RelocateDialog> create(
         Gtk::Window& parent,
-        Glib::RefPtr<TrCore> const& core,
+        Glib::RefPtr<Session> const& core,
         std::vector<int> const& torrent_ids);
 
 protected:
-    RelocateDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core, std::vector<int> const& torrent_ids);
+    RelocateDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core, std::vector<int> const& torrent_ids);
 
 private:
     class Impl;
diff --git a/gtk/tr-core.cc b/gtk/Session.cc
similarity index 91%
rename from gtk/tr-core.cc
rename to gtk/Session.cc
index 052fc4950..597190e3b 100644
--- a/gtk/tr-core.cc
+++ b/gtk/Session.cc
@@ -37,12 +37,12 @@
 #include <libtransmission/utils.h> /* tr_free */
 #include <libtransmission/variant.h>
 
-#include "actions.h"
-#include "conf.h"
-#include "notify.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "Actions.h"
+#include "Notify.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 namespace
 {
@@ -70,10 +70,10 @@ private:
 
 } // namespace
 
-class TrCore::Impl
+class Session::Impl
 {
 public:
-    Impl(TrCore& core, tr_session* session);
+    Impl(Session& core, tr_session* session);
 
     tr_session* close();
 
@@ -104,7 +104,7 @@ public:
     sigc::signal<void(bool)> signal_port_tested;
 
 private:
-    Glib::RefPtr<TrCore> get_core_ptr() const;
+    Glib::RefPtr<Session> get_core_ptr() const;
 
     bool is_busy();
     void add_to_busy(int addMe);
@@ -141,7 +141,7 @@ private:
     void on_torrent_metadata_changed(tr_torrent* tor);
 
 private:
-    TrCore& core_;
+    Session& core_;
 
     Glib::RefPtr<Gio::FileMonitor> monitor_;
     sigc::connection monitor_tag_;
@@ -182,37 +182,37 @@ TorrentModelColumns::TorrentModelColumns()
 
 TorrentModelColumns const torrent_cols;
 
-Glib::RefPtr<TrCore> TrCore::Impl::get_core_ptr() const
+Glib::RefPtr<Session> Session::Impl::get_core_ptr() const
 {
     core_.reference();
-    return Glib::RefPtr<TrCore>(&core_);
+    return Glib::RefPtr<Session>(&core_);
 }
 
 /***
 ****
 ***/
 
-Glib::RefPtr<Gtk::ListStore> TrCore::Impl::get_raw_model() const
+Glib::RefPtr<Gtk::ListStore> Session::Impl::get_raw_model() const
 {
     return raw_model_;
 }
 
-Glib::RefPtr<Gtk::TreeModel> TrCore::get_model() const
+Glib::RefPtr<Gtk::TreeModel> Session::get_model() const
 {
     return impl_->get_model();
 }
 
-Glib::RefPtr<Gtk::TreeModelSort> TrCore::Impl::get_model() const
+Glib::RefPtr<Gtk::TreeModelSort> Session::Impl::get_model() const
 {
     return sorted_model_;
 }
 
-tr_session* TrCore::get_session() const
+tr_session* Session::get_session() const
 {
     return impl_->get_session();
 }
 
-tr_session* TrCore::Impl::get_session() const
+tr_session* Session::Impl::get_session() const
 {
     return session_;
 }
@@ -221,12 +221,12 @@ tr_session* TrCore::Impl::get_session() const
 ****  BUSY
 ***/
 
-bool TrCore::Impl::is_busy()
+bool Session::Impl::is_busy()
 {
     return busy_count_ > 0;
 }
 
-void TrCore::Impl::add_to_busy(int addMe)
+void Session::Impl::add_to_busy(int addMe)
 {
     bool const wasBusy = is_busy();
 
@@ -238,12 +238,12 @@ void TrCore::Impl::add_to_busy(int addMe)
     }
 }
 
-void TrCore::Impl::inc_busy()
+void Session::Impl::inc_busy()
 {
     add_to_busy(1);
 }
 
-void TrCore::Impl::dec_busy()
+void Session::Impl::dec_busy()
 {
     add_to_busy(-1);
 }
@@ -561,7 +561,7 @@ int compare_by_state(Gtk::TreeModel::iterator const& a, Gtk::TreeModel::iterator
 
 } // namespace
 
-void TrCore::Impl::set_sort_mode(std::string const& mode, bool is_reversed)
+void Session::Impl::set_sort_mode(std::string const& mode, bool is_reversed)
 {
     auto const& col = torrent_cols.torrent;
     Gtk::TreeSortable::SlotCompare sort_func;
@@ -647,7 +647,7 @@ void rename_torrent(Glib::RefPtr<Gio::File> const& file)
 
 } // namespace
 
-bool TrCore::Impl::watchdir_idle()
+bool Session::Impl::watchdir_idle()
 {
     std::vector<Glib::RefPtr<Gio::File>> changing;
     std::vector<Glib::RefPtr<Gio::File>> unchanging;
@@ -694,7 +694,7 @@ bool TrCore::Impl::watchdir_idle()
 }
 
 /* If this file is a torrent, add it to our list */
-void TrCore::Impl::watchdir_monitor_file(Glib::RefPtr<Gio::File> const& file)
+void Session::Impl::watchdir_monitor_file(Glib::RefPtr<Gio::File> const& file)
 {
     auto const filename = file->get_path();
     bool const is_torrent = Glib::str_has_suffix(filename, ".torrent");
@@ -720,7 +720,7 @@ void TrCore::Impl::watchdir_monitor_file(Glib::RefPtr<Gio::File> const& file)
 }
 
 /* GFileMonitor noticed a file was created */
-void TrCore::Impl::on_file_changed_in_watchdir(
+void Session::Impl::on_file_changed_in_watchdir(
     Glib::RefPtr<Gio::File> const& file,
     Glib::RefPtr<Gio::File> const& /*other_type*/,
     Gio::FileMonitorEvent event_type)
@@ -732,7 +732,7 @@ void TrCore::Impl::on_file_changed_in_watchdir(
 }
 
 /* walk through the pre-existing files in the watchdir */
-void TrCore::Impl::watchdir_scan()
+void Session::Impl::watchdir_scan()
 {
     auto const dirname = gtr_pref_string_get(TR_KEY_watch_dir);
 
@@ -748,7 +748,7 @@ void TrCore::Impl::watchdir_scan()
     }
 }
 
-void TrCore::Impl::watchdir_update()
+void Session::Impl::watchdir_update()
 {
     bool const is_enabled = gtr_pref_flag_get(TR_KEY_watch_dir_enabled);
     auto const dir = Gio::File::create_for_path(gtr_pref_string_get(TR_KEY_watch_dir));
@@ -777,7 +777,7 @@ void TrCore::Impl::watchdir_update()
 ****
 ***/
 
-void TrCore::Impl::on_pref_changed(tr_quark const key)
+void Session::Impl::on_pref_changed(tr_quark const key)
 {
     switch (key)
     {
@@ -816,20 +816,20 @@ void TrCore::Impl::on_pref_changed(tr_quark const key)
 ***
 **/
 
-Glib::RefPtr<TrCore> TrCore::create(tr_session* session)
+Glib::RefPtr<Session> Session::create(tr_session* session)
 {
-    return Glib::make_refptr_for_instance(new TrCore(session));
+    return Glib::make_refptr_for_instance(new Session(session));
 }
 
-TrCore::TrCore(tr_session* session)
-    : Glib::ObjectBase(typeid(TrCore))
+Session::Session(tr_session* session)
+    : Glib::ObjectBase(typeid(Session))
     , impl_(std::make_unique<Impl>(*this, session))
 {
 }
 
-TrCore::~TrCore() = default;
+Session::~Session() = default;
 
-TrCore::Impl::Impl(TrCore& core, tr_session* session)
+Session::Impl::Impl(Session& core, tr_session* session)
     : core_(core)
     , session_(session)
 {
@@ -847,12 +847,12 @@ TrCore::Impl::Impl(TrCore& core, tr_session* session)
     signal_prefs_changed.connect([this](auto key) { on_pref_changed(key); });
 }
 
-tr_session* TrCore::close()
+tr_session* Session::close()
 {
     return impl_->close();
 }
 
-tr_session* TrCore::Impl::close()
+tr_session* Session::Impl::close()
 {
     auto* session = session_;
 
@@ -871,7 +871,7 @@ tr_session* TrCore::Impl::close()
 
 /* this is called in the libtransmission thread, *NOT* the GTK+ thread,
    so delegate to the GTK+ thread before calling notify's dbus code... */
-void TrCore::Impl::on_torrent_completeness_changed(tr_torrent* tor, tr_completeness completeness, bool was_running)
+void Session::Impl::on_torrent_completeness_changed(tr_torrent* tor, tr_completeness completeness, bool was_running)
 {
     if (was_running && completeness != TR_LEECH && tr_torrentStat(tor)->sizeWhenDone != 0)
     {
@@ -899,7 +899,7 @@ Glib::ustring get_collated_name(tr_torrent const* tor)
 
 struct metadata_callback_data
 {
-    TrCore* core;
+    Session* core;
     int torrent_id;
 };
 
@@ -920,7 +920,7 @@ Gtk::TreeModel::iterator find_row_from_torrent_id(Glib::RefPtr<Gtk::TreeModel> c
 
 /* this is called in the libtransmission thread, *NOT* the GTK+ thread,
    so delegate to the GTK+ thread before changing our list store... */
-void TrCore::Impl::on_torrent_metadata_changed(tr_torrent* tor)
+void Session::Impl::on_torrent_metadata_changed(tr_torrent* tor)
 {
     Glib::signal_idle().connect(
         [this, core = get_core_ptr(), torrent_id = tr_torrentId(tor)]()
@@ -972,13 +972,13 @@ bool is_torrent_active(tr_stat const* st)
 
 } // namespace
 
-void TrCore::add_torrent(tr_torrent* tor, bool do_notify)
+void Session::add_torrent(tr_torrent* tor, bool do_notify)
 {
     ScopedModelSortBlocker disable_sort(*gtr_get_ptr(impl_->get_model()));
     impl_->add_torrent(tor, do_notify);
 }
 
-void TrCore::Impl::add_torrent(tr_torrent* tor, bool do_notify)
+void Session::Impl::add_torrent(tr_torrent* tor, bool do_notify)
 {
     if (tor != nullptr)
     {
@@ -1020,7 +1020,7 @@ void TrCore::Impl::add_torrent(tr_torrent* tor, bool do_notify)
     }
 }
 
-tr_torrent* TrCore::Impl::create_new_torrent(tr_ctor* ctor)
+tr_torrent* Session::Impl::create_new_torrent(tr_ctor* ctor)
 {
     bool do_trash = false;
 
@@ -1050,7 +1050,7 @@ tr_torrent* TrCore::Impl::create_new_torrent(tr_ctor* ctor)
     return tor;
 }
 
-int TrCore::Impl::add_ctor(tr_ctor* ctor, bool do_prompt, bool do_notify)
+int Session::Impl::add_ctor(tr_ctor* ctor, bool do_prompt, bool do_notify)
 {
     tr_info inf;
     auto err = tr_torrentParse(ctor, &inf);
@@ -1120,7 +1120,7 @@ void core_apply_defaults(tr_ctor* ctor)
 
 } // namespace
 
-void TrCore::add_ctor(tr_ctor* ctor)
+void Session::add_ctor(tr_ctor* ctor)
 {
     bool const do_notify = false;
     bool const do_prompt = gtr_pref_flag_get(TR_KEY_show_options_window);
@@ -1132,7 +1132,7 @@ void TrCore::add_ctor(tr_ctor* ctor)
 ****
 ***/
 
-void TrCore::Impl::add_file_async_callback(
+void Session::Impl::add_file_async_callback(
     Glib::RefPtr<Gio::File> const& file,
     Glib::RefPtr<Gio::AsyncResult>& result,
     tr_ctor* ctor,
@@ -1165,7 +1165,7 @@ void TrCore::Impl::add_file_async_callback(
     dec_busy();
 }
 
-bool TrCore::Impl::add_file(Glib::RefPtr<Gio::File> const& file, bool do_start, bool do_prompt, bool do_notify)
+bool Session::Impl::add_file(Glib::RefPtr<Gio::File> const& file, bool do_start, bool do_prompt, bool do_notify)
 {
     bool handled = false;
     auto const* const session = get_session();
@@ -1236,12 +1236,12 @@ bool TrCore::Impl::add_file(Glib::RefPtr<Gio::File> const& file, bool do_start,
     return handled;
 }
 
-bool TrCore::add_from_url(Glib::ustring const& uri)
+bool Session::add_from_url(Glib::ustring const& uri)
 {
     return impl_->add_from_url(uri);
 }
 
-bool TrCore::Impl::add_from_url(Glib::ustring const& uri)
+bool Session::Impl::add_from_url(Glib::ustring const& uri)
 {
     bool handled;
     bool const do_start = gtr_pref_flag_get(TR_KEY_start_added_torrents);
@@ -1255,12 +1255,12 @@ bool TrCore::Impl::add_from_url(Glib::ustring const& uri)
     return handled;
 }
 
-void TrCore::add_files(std::vector<Glib::RefPtr<Gio::File>> const& files, bool do_start, bool do_prompt, bool do_notify)
+void Session::add_files(std::vector<Glib::RefPtr<Gio::File>> const& files, bool do_start, bool do_prompt, bool do_notify)
 {
     impl_->add_files(files, do_start, do_prompt, do_notify);
 }
 
-void TrCore::Impl::add_files(std::vector<Glib::RefPtr<Gio::File>> const& files, bool do_start, bool do_prompt, bool do_notify)
+void Session::Impl::add_files(std::vector<Glib::RefPtr<Gio::File>> const& files, bool do_start, bool do_prompt, bool do_notify)
 {
     for (auto const& file : files)
     {
@@ -1270,18 +1270,18 @@ void TrCore::Impl::add_files(std::vector<Glib::RefPtr<Gio::File>> const& files,
     torrents_added();
 }
 
-void TrCore::torrents_added()
+void Session::torrents_added()
 {
     impl_->torrents_added();
 }
 
-void TrCore::Impl::torrents_added()
+void Session::Impl::torrents_added()
 {
     update();
     signal_add_error.emit(ERR_NO_MORE_TORRENTS, {});
 }
 
-void TrCore::torrent_changed(int id)
+void Session::torrent_changed(int id)
 {
     auto const model = impl_->get_raw_model();
 
@@ -1291,7 +1291,7 @@ void TrCore::torrent_changed(int id)
     }
 }
 
-void TrCore::remove_torrent(int id, bool delete_local_data)
+void Session::remove_torrent(int id, bool delete_local_data)
 {
     auto* tor = find_torrent(id);
 
@@ -1313,7 +1313,7 @@ void TrCore::remove_torrent(int id, bool delete_local_data)
     }
 }
 
-void TrCore::load(bool forcePaused)
+void Session::load(bool forcePaused)
 {
     tr_ctor* ctor;
     tr_torrent** torrents;
@@ -1341,7 +1341,7 @@ void TrCore::load(bool forcePaused)
     tr_ctorFree(ctor);
 }
 
-void TrCore::clear()
+void Session::clear()
 {
     impl_->get_raw_model()->clear();
 }
@@ -1436,12 +1436,12 @@ void update_foreach(Gtk::TreeModel::Row const& row)
 
 } // namespace
 
-void TrCore::update()
+void Session::update()
 {
     impl_->update();
 }
 
-void TrCore::Impl::update()
+void Session::Impl::update()
 {
     /* update the model */
     for (auto const& row : raw_model_->children())
@@ -1529,7 +1529,7 @@ void gtr_uninhibit_hibernation(guint inhibit_cookie)
 
 } // namespace
 
-void TrCore::Impl::set_hibernation_allowed(bool allowed)
+void Session::Impl::set_hibernation_allowed(bool allowed)
 {
     inhibit_allowed_ = allowed;
 
@@ -1552,7 +1552,7 @@ void TrCore::Impl::set_hibernation_allowed(bool allowed)
     }
 }
 
-void TrCore::Impl::maybe_inhibit_hibernation()
+void Session::Impl::maybe_inhibit_hibernation()
 {
     /* hibernation is allowed if EITHER
      * (a) the "inhibit" pref is turned off OR
@@ -1565,13 +1565,13 @@ void TrCore::Impl::maybe_inhibit_hibernation()
 ***  Prefs
 **/
 
-void TrCore::Impl::commit_prefs_change(tr_quark const key)
+void Session::Impl::commit_prefs_change(tr_quark const key)
 {
     signal_prefs_changed.emit(key);
     gtr_pref_save(session_);
 }
 
-void TrCore::set_pref(tr_quark const key, std::string const& newval)
+void Session::set_pref(tr_quark const key, std::string const& newval)
 {
     if (newval != gtr_pref_string_get(key))
     {
@@ -1580,7 +1580,7 @@ void TrCore::set_pref(tr_quark const key, std::string const& newval)
     }
 }
 
-void TrCore::set_pref(tr_quark const key, bool newval)
+void Session::set_pref(tr_quark const key, bool newval)
 {
     if (newval != gtr_pref_flag_get(key))
     {
@@ -1589,7 +1589,7 @@ void TrCore::set_pref(tr_quark const key, bool newval)
     }
 }
 
-void TrCore::set_pref(tr_quark const key, int newval)
+void Session::set_pref(tr_quark const key, int newval)
 {
     if (newval != gtr_pref_int_get(key))
     {
@@ -1598,7 +1598,7 @@ void TrCore::set_pref(tr_quark const key, int newval)
     }
 }
 
-void TrCore::set_pref(tr_quark const key, double newval)
+void Session::set_pref(tr_quark const key, double newval)
 {
     if (gtr_compare_double(newval, gtr_pref_double_get(key), 4))
     {
@@ -1620,7 +1620,7 @@ namespace
 
 int nextTag = 1;
 
-typedef void (*server_response_func)(TrCore* core, tr_variant* response, gpointer user_data);
+typedef void (*server_response_func)(Session* core, tr_variant* response, gpointer user_data);
 
 struct pending_request_data
 {
@@ -1666,7 +1666,7 @@ void core_read_rpc_response(tr_session* /*session*/, tr_variant* response, void*
 
 } // namespace
 
-void TrCore::Impl::send_rpc_request(tr_variant const* request, int tag, std::function<void(tr_variant*)> const& response_func)
+void Session::Impl::send_rpc_request(tr_variant const* request, int tag, std::function<void(tr_variant*)> const& response_func)
 {
     if (session_ == nullptr)
     {
@@ -1698,7 +1698,7 @@ void TrCore::Impl::send_rpc_request(tr_variant const* request, int tag, std::fun
 ****  Sending a test-port request via RPC
 ***/
 
-void TrCore::port_test()
+void Session::port_test()
 {
     int const tag = nextTag;
     ++nextTag;
@@ -1730,7 +1730,7 @@ void TrCore::port_test()
 ****  Updating a blocklist via RPC
 ***/
 
-void TrCore::blocklist_update()
+void Session::blocklist_update()
 {
     int const tag = nextTag;
     ++nextTag;
@@ -1767,7 +1767,7 @@ void TrCore::blocklist_update()
 ****
 ***/
 
-void TrCore::exec(tr_variant const* top)
+void Session::exec(tr_variant const* top)
 {
     int const tag = nextTag;
     ++nextTag;
@@ -1779,17 +1779,17 @@ void TrCore::exec(tr_variant const* top)
 ****
 ***/
 
-size_t TrCore::get_torrent_count() const
+size_t Session::get_torrent_count() const
 {
     return impl_->get_raw_model()->children().size();
 }
 
-size_t TrCore::get_active_torrent_count() const
+size_t Session::get_active_torrent_count() const
 {
     return impl_->get_active_torrent_count();
 }
 
-size_t TrCore::Impl::get_active_torrent_count() const
+size_t Session::Impl::get_active_torrent_count() const
 {
     size_t activeCount = 0;
 
@@ -1804,7 +1804,7 @@ size_t TrCore::Impl::get_active_torrent_count() const
     return activeCount;
 }
 
-tr_torrent* TrCore::find_torrent(int id) const
+tr_torrent* Session::find_torrent(int id) const
 {
     tr_torrent* tor = nullptr;
 
@@ -1816,7 +1816,7 @@ tr_torrent* TrCore::find_torrent(int id) const
     return tor;
 }
 
-void TrCore::open_folder(int torrent_id)
+void Session::open_folder(int torrent_id)
 {
     auto const* tor = find_torrent(torrent_id);
 
@@ -1836,32 +1836,32 @@ void TrCore::open_folder(int torrent_id)
     }
 }
 
-sigc::signal<void(TrCore::ErrorCode, Glib::ustring const&)>& TrCore::signal_add_error()
+sigc::signal<void(Session::ErrorCode, Glib::ustring const&)>& Session::signal_add_error()
 {
     return impl_->signal_add_error;
 }
 
-sigc::signal<void(tr_ctor*)>& TrCore::signal_add_prompt()
+sigc::signal<void(tr_ctor*)>& Session::signal_add_prompt()
 {
     return impl_->signal_add_prompt;
 }
 
-sigc::signal<void(int)>& TrCore::signal_blocklist_updated()
+sigc::signal<void(int)>& Session::signal_blocklist_updated()
 {
     return impl_->signal_blocklist_updated;
 }
 
-sigc::signal<void(bool)>& TrCore::signal_busy()
+sigc::signal<void(bool)>& Session::signal_busy()
 {
     return impl_->signal_busy;
 }
 
-sigc::signal<void(tr_quark)>& TrCore::signal_prefs_changed()
+sigc::signal<void(tr_quark)>& Session::signal_prefs_changed()
 {
     return impl_->signal_prefs_changed;
 }
 
-sigc::signal<void(bool)>& TrCore::signal_port_tested()
+sigc::signal<void(bool)>& Session::signal_port_tested()
 {
     return impl_->signal_port_tested;
 }
diff --git a/gtk/tr-core.h b/gtk/Session.h
similarity index 97%
rename from gtk/tr-core.h
rename to gtk/Session.h
index e5cb14891..4fe3bbec1 100644
--- a/gtk/tr-core.h
+++ b/gtk/Session.h
@@ -34,7 +34,7 @@
 
 #define TR_RESOURCE_PATH "/com/transmissionbt/transmission/"
 
-class TrCore : public Glib::Object
+class Session : public Glib::Object
 {
 public:
     enum ErrorCode
@@ -45,9 +45,9 @@ public:
     };
 
 public:
-    ~TrCore() override;
+    ~Session() override;
 
-    static Glib::RefPtr<TrCore> create(tr_session* session);
+    static Glib::RefPtr<Session> create(tr_session* session);
 
     tr_session* close();
 
@@ -140,7 +140,7 @@ public:
     sigc::signal<void(bool)>& signal_port_tested();
 
 protected:
-    TrCore(tr_session* session);
+    Session(tr_session* session);
 
 private:
     class Impl;
diff --git a/gtk/stats.cc b/gtk/StatsDialog.cc
similarity index 92%
rename from gtk/stats.cc
rename to gtk/StatsDialog.cc
index 4e176da47..b4528b73c 100644
--- a/gtk/stats.cc
+++ b/gtk/StatsDialog.cc
@@ -9,11 +9,11 @@
 #include <glibmm.h>
 #include <glibmm/i18n.h>
 
-#include "hig.h"
-#include "stats.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "StatsDialog.h"
+#include "Utils.h"
 
 enum
 {
@@ -23,7 +23,7 @@ enum
 class StatsDialog::Impl
 {
 public:
-    Impl(StatsDialog& dialog, Glib::RefPtr<TrCore> const& core);
+    Impl(StatsDialog& dialog, Glib::RefPtr<Session> const& core);
     ~Impl();
 
 private:
@@ -32,7 +32,7 @@ private:
 
 private:
     StatsDialog& dialog_;
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
 
     Gtk::Label* one_up_lb_;
     Gtk::Label* one_down_lb_;
@@ -118,12 +118,12 @@ void StatsDialog::Impl::dialogResponse(int response)
     }
 }
 
-std::unique_ptr<StatsDialog> StatsDialog::create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+std::unique_ptr<StatsDialog> StatsDialog::create(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
 {
     return std::unique_ptr<StatsDialog>(new StatsDialog(parent, core));
 }
 
-StatsDialog::StatsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
+StatsDialog::StatsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core)
     : Gtk::Dialog(_("Statistics"), parent)
     , impl_(std::make_unique<Impl>(*this, core))
 {
@@ -131,7 +131,7 @@ StatsDialog::StatsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core)
 
 StatsDialog::~StatsDialog() = default;
 
-StatsDialog::Impl::Impl(StatsDialog& dialog, Glib::RefPtr<TrCore> const& core)
+StatsDialog::Impl::Impl(StatsDialog& dialog, Glib::RefPtr<Session> const& core)
     : dialog_(dialog)
     , core_(core)
 {
diff --git a/gtk/stats.h b/gtk/StatsDialog.h
similarity index 77%
rename from gtk/stats.h
rename to gtk/StatsDialog.h
index ba3d7c046..2a665d42f 100644
--- a/gtk/stats.h
+++ b/gtk/StatsDialog.h
@@ -12,17 +12,17 @@
 
 #include <gtkmm.h>
 
-class TrCore;
+class Session;
 
 class StatsDialog : public Gtk::Dialog
 {
 public:
     ~StatsDialog() override;
 
-    static std::unique_ptr<StatsDialog> create(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    static std::unique_ptr<StatsDialog> create(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 protected:
-    StatsDialog(Gtk::Window& parent, Glib::RefPtr<TrCore> const& core);
+    StatsDialog(Gtk::Window& parent, Glib::RefPtr<Session> const& core);
 
 private:
     class Impl;
diff --git a/gtk/tr-icon.cc b/gtk/SystemTrayIcon.cc
similarity index 93%
rename from gtk/tr-icon.cc
rename to gtk/SystemTrayIcon.cc
index 82b346d7d..54cd6d8b8 100644
--- a/gtk/tr-icon.cc
+++ b/gtk/SystemTrayIcon.cc
@@ -17,17 +17,17 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h>
 
-#include "actions.h"
-#include "tr-core.h"
-#include "tr-icon.h"
-#include "util.h"
+#include "Actions.h"
+#include "Session.h"
+#include "SystemTrayIcon.h"
+#include "Utils.h"
 
 #define ICON_NAME "transmission"
 
 class SystemTrayIcon::Impl
 {
 public:
-    Impl(Glib::RefPtr<TrCore> const& core);
+    Impl(Glib::RefPtr<Session> const& core);
     ~Impl();
 
     void refresh();
@@ -37,7 +37,7 @@ private:
     void popup(guint button, guint when);
 
 private:
-    Glib::RefPtr<TrCore> const core_;
+    Glib::RefPtr<Session> const core_;
 
     Gtk::Menu* menu_;
 
@@ -167,7 +167,7 @@ std::string getIconName()
 
 } // namespace
 
-SystemTrayIcon::SystemTrayIcon(Glib::RefPtr<TrCore> const& core)
+SystemTrayIcon::SystemTrayIcon(Glib::RefPtr<Session> const& core)
     : impl_(std::make_unique<Impl>(core))
 {
 }
@@ -179,7 +179,7 @@ void SystemTrayIcon::refresh()
     impl_->refresh();
 }
 
-SystemTrayIcon::Impl::Impl(Glib::RefPtr<TrCore> const& core)
+SystemTrayIcon::Impl::Impl(Glib::RefPtr<Session> const& core)
     : core_(core)
 {
     auto const icon_name = getIconName();
diff --git a/gtk/tr-icon.h b/gtk/SystemTrayIcon.h
similarity index 82%
rename from gtk/tr-icon.h
rename to gtk/SystemTrayIcon.h
index 47a5c5a1c..c3081cf52 100644
--- a/gtk/tr-icon.h
+++ b/gtk/SystemTrayIcon.h
@@ -10,10 +10,12 @@
 
 #include <memory>
 
+class Session;
+
 class SystemTrayIcon
 {
 public:
-    SystemTrayIcon(Glib::RefPtr<TrCore> const& core);
+    SystemTrayIcon(Glib::RefPtr<Session> const& core);
     ~SystemTrayIcon();
 
     void refresh();
diff --git a/gtk/torrent-cell-renderer.cc b/gtk/TorrentCellRenderer.cc
similarity index 99%
rename from gtk/torrent-cell-renderer.cc
rename to gtk/TorrentCellRenderer.cc
index 78e4835d5..a6a2fbd06 100644
--- a/gtk/torrent-cell-renderer.cc
+++ b/gtk/TorrentCellRenderer.cc
@@ -14,10 +14,10 @@
 #include <libtransmission/transmission.h>
 #include <libtransmission/utils.h> /* tr_truncd() */
 
-#include "hig.h"
-#include "icons.h"
-#include "torrent-cell-renderer.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "IconCache.h"
+#include "TorrentCellRenderer.h"
+#include "Utils.h"
 
 /* #define TEST_RTL */
 
diff --git a/gtk/torrent-cell-renderer.h b/gtk/TorrentCellRenderer.h
similarity index 100%
rename from gtk/torrent-cell-renderer.h
rename to gtk/TorrentCellRenderer.h
diff --git a/gtk/util.cc b/gtk/Utils.cc
similarity index 89%
rename from gtk/util.cc
rename to gtk/Utils.cc
index 21d92fa42..eb1e44148 100644
--- a/gtk/util.cc
+++ b/gtk/Utils.cc
@@ -22,11 +22,11 @@
 #include <libtransmission/web.h> /* tr_webResponseStr() */
 #include <libtransmission/version.h> /* SHORT_VERSION_STRING */
 
-#include "conf.h"
-#include "hig.h"
-#include "tr-core.h"
-#include "tr-prefs.h"
-#include "util.h"
+#include "HigWorkarea.h"
+#include "Prefs.h"
+#include "PrefsDialog.h"
+#include "Session.h"
+#include "Utils.h"
 
 /***
 ****  UNITS
@@ -574,74 +574,3 @@ void gtr_label_set_text(Gtk::Label& lb, Glib::ustring const& newstr)
         lb.set_text(newstr);
     }
 }
-
-/***
-****
-***/
-
-class FreeSpaceLabel::Impl
-{
-public:
-    Impl(FreeSpaceLabel& label, Glib::RefPtr<TrCore> const& core, std::string const& dir);
-    ~Impl();
-
-    void set_dir(std::string const& dir);
-
-private:
-    bool on_freespace_timer();
-
-private:
-    FreeSpaceLabel& label_;
-    Glib::RefPtr<TrCore> const core_;
-    std::string dir_;
-    sigc::connection timer_id_;
-};
-
-FreeSpaceLabel::Impl::~Impl()
-{
-    timer_id_.disconnect();
-}
-
-bool FreeSpaceLabel::Impl::on_freespace_timer()
-{
-    auto* const session = core_->get_session();
-    if (session == nullptr)
-    {
-        return false;
-    }
-
-    auto const bytes = tr_sessionGetDirFreeSpace(session, dir_.c_str());
-    auto const text = bytes < 0 ? _("Error") : gtr_sprintf(_("%s free"), tr_strlsize(bytes));
-    auto const markup = gtr_sprintf("<i>%s</i>", text);
-    label_.set_markup(markup);
-
-    return true;
-}
-
-FreeSpaceLabel::FreeSpaceLabel(Glib::RefPtr<TrCore> const& core, std::string const& dir)
-    : Gtk::Label()
-    , impl_(std::make_unique<Impl>(*this, core, dir))
-{
-}
-
-FreeSpaceLabel::~FreeSpaceLabel() = default;
-
-FreeSpaceLabel::Impl::Impl(FreeSpaceLabel& label, Glib::RefPtr<TrCore> const& core, std::string const& dir)
-    : label_(label)
-    , core_(core)
-    , dir_(dir)
-{
-    timer_id_ = Glib::signal_timeout().connect_seconds(sigc::mem_fun(this, &Impl::on_freespace_timer), 3);
-    on_freespace_timer();
-}
-
-void FreeSpaceLabel::set_dir(std::string const& dir)
-{
-    impl_->set_dir(dir);
-}
-
-void FreeSpaceLabel::Impl::set_dir(std::string const& dir)
-{
-    dir_ = dir;
-    on_freespace_timer();
-}
diff --git a/gtk/util.h b/gtk/Utils.h
similarity index 95%
rename from gtk/util.h
rename to gtk/Utils.h
index 96c98cfe0..5ac7ce86b 100644
--- a/gtk/util.h
+++ b/gtk/Utils.h
@@ -10,6 +10,7 @@
 
 #include <functional>
 #include <sys/types.h>
+
 #include <glibmm.h>
 #include <gtkmm.h>
 
@@ -102,25 +103,6 @@ void gtr_combo_box_set_active_enum(Gtk::ComboBox&, int value);
 ****
 ***/
 
-class TrCore;
-
-class FreeSpaceLabel : public Gtk::Label
-{
-public:
-    FreeSpaceLabel(Glib::RefPtr<TrCore> const& core, std::string const& dir = {});
-    ~FreeSpaceLabel() override;
-
-    void set_dir(std::string const& dir);
-
-private:
-    class Impl;
-    std::unique_ptr<Impl> const impl_;
-};
-
-/***
-****
-***/
-
 void gtr_unrecognized_url_dialog(Gtk::Widget& parent, Glib::ustring const& url);
 
 void gtr_add_torrent_error_dialog(
diff --git a/gtk/main.cc b/gtk/main.cc
index 388b3eb7c..3a8455fdf 100644
--- a/gtk/main.cc
+++ b/gtk/main.cc
@@ -30,10 +30,10 @@
 #include <libtransmission/utils.h>
 #include <libtransmission/version.h>
 
-#include "application.h"
-#include "conf.h"
-#include "notify.h"
-#include "util.h"
+#include "Application.h"
+#include "Notify.h"
+#include "Prefs.h"
+#include "Utils.h"
 
 #define MY_CONFIG_NAME "transmission"
 #define MY_READABLE_NAME "transmission-gtk"