Add internal preference for large screen UI.

app/src/main/java/org/thoughtcrime/securesms/MainActivity.kt

@@ -240,7 +240,7 @@ class MainActivity : PassphraseRequiredActivity(), VoiceNoteMediaControllerOwner
 
       LaunchedEffect(detailLocation) {
         if (detailLocation is MainNavigationDetailLocation.Conversation) {
-          if (RemoteConfig.largeScreenUi) {
+          if (SignalStore.internal.largeScreenUi) {
             scaffoldNavigator.navigateTo(ThreePaneScaffoldRole.Primary, detailLocation)
           } else {
             startActivity((detailLocation as MainNavigationDetailLocation.Conversation).intent)

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsFragment.kt

@@ -163,6 +163,17 @@ class InternalSettingsFragment : DSLSettingsFragment(R.string.preferences__inter
       )
       dividerPref()
 
+      sectionHeaderPref(DSLSettingsText.from("App UI"))
+
+      switchPref(
+        title = DSLSettingsText.from("Enable new split pane UI."),
+        summary = DSLSettingsText.from("Warning: Some bugs and non functional buttons are expected."),
+        isChecked = state.largeScreenUi,
+        onClick = {
+          viewModel.setUseLargeScreenUi(!state.largeScreenUi)
+        }
+      )
+
       sectionHeaderPref(DSLSettingsText.from("Playgrounds"))
 
       clickPref(

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsState.kt

@@ -25,5 +25,6 @@ data class InternalSettingsState(
   val useConversationItemV2ForMedia: Boolean,
   val hasPendingOneTimeDonation: Boolean,
   val hevcEncoding: Boolean,
-  val newCallingUi: Boolean
+  val newCallingUi: Boolean,
+  val largeScreenUi: Boolean
 )

app/src/main/java/org/thoughtcrime/securesms/components/settings/app/internal/InternalSettingsViewModel.kt

@@ -166,7 +166,8 @@ class InternalSettingsViewModel(private val repository: InternalSettingsReposito
     useConversationItemV2ForMedia = SignalStore.internal.useConversationItemV2Media,
     hasPendingOneTimeDonation = SignalStore.inAppPayments.getPendingOneTimeDonation() != null,
     hevcEncoding = SignalStore.internal.hevcEncoding,
-    newCallingUi = SignalStore.internal.newCallingUi
+    newCallingUi = SignalStore.internal.newCallingUi,
+    largeScreenUi = SignalStore.internal.largeScreenUi
   )
 
   fun onClearOnboardingState() {
@@ -182,6 +183,11 @@ class InternalSettingsViewModel(private val repository: InternalSettingsReposito
     refresh()
   }
 
+  fun setUseLargeScreenUi(largeScreenUi: Boolean) {
+    SignalStore.internal.largeScreenUi = largeScreenUi
+    refresh()
+  }
+
   class Factory(private val repository: InternalSettingsRepository) : ViewModelProvider.Factory {
     override fun <T : ViewModel> create(modelClass: Class<T>): T {
       return requireNotNull(modelClass.cast(InternalSettingsViewModel(repository)))

app/src/main/java/org/thoughtcrime/securesms/keyvalue/InternalValues.kt

@@ -28,12 +28,18 @@ class InternalValues internal constructor(store: KeyValueStore) : SignalStoreVal
     const val WEB_SOCKET_SHADOWING_STATS: String = "internal.web_socket_shadowing_stats"
     const val ENCODE_HEVC: String = "internal.hevc_encoding"
     const val NEW_CALL_UI: String = "internal.new.call.ui"
+    const val LARGE_SCREEN_UI: String = "internal.large.screen.ui"
   }
 
   public override fun onFirstEverAppLaunch() = Unit
 
   public override fun getKeysToIncludeInBackup(): List<String> = emptyList()
 
+  /**
+   * Enable or disable the large screen UI.
+   */
+  var largeScreenUi by booleanValue(LARGE_SCREEN_UI, false).defaultForExternalUsers()
+
   /**
    * Members will not be added directly to a GV2 even if they could be.
    */

app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt

@@ -32,6 +32,7 @@ import androidx.window.core.ExperimentalWindowCoreApi
 import androidx.window.core.layout.WindowHeightSizeClass
 import androidx.window.core.layout.WindowWidthSizeClass
 import org.signal.core.ui.compose.Previews
+import org.thoughtcrime.securesms.keyvalue.SignalStore
 import org.thoughtcrime.securesms.main.MainNavigationBar
 import org.thoughtcrime.securesms.main.MainNavigationRail
 import org.thoughtcrime.securesms.main.MainNavigationState
@@ -72,7 +73,7 @@ enum class WindowSizeClass(
     fun Resources.getWindowSizeClass(): WindowSizeClass {
       val orientation = configuration.orientation
 
-      if (!RemoteConfig.largeScreenUi) {
+      if (isForcedCompact()) {
         return getCompactSizeClassForOrientation(orientation)
       }
 
@@ -86,7 +87,7 @@ enum class WindowSizeClass(
     }
 
     fun isForcedCompact(): Boolean {
-      return !RemoteConfig.largeScreenUi
+      return !SignalStore.internal.largeScreenUi
     }
 
     @Composable