re-add macOS Fullscreen support (#3261)

* re-add macOS Fullscreen support

re added Full Screen support for macOS. Also refactored window methods in Controller.mm and moved to their own category - ControllerWindowMethods.mm

This has currently only been tested on macOS Monterey, and should be good on earlier versions - but perhaps needs testing on earlier versions of macOS.

fixes #3231 #3234

macosx/MessageWindowController.mm

@@ -58,9 +58,6 @@
     [window setFrameUsingName:@"MessageWindowFrame"];
     window.restorationClass = [self class];
 
-    //disable fullscreen support
-    [window setCollectionBehavior:NSWindowCollectionBehaviorFullScreenNone];
-
     [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(resizeColumn)
                                                name:NSTableViewColumnDidResizeNotification
                                              object:self.fMessageTable];
@@ -69,6 +66,9 @@
 
     self.window.title = NSLocalizedString(@"Message Log", "Message window -> title");
 
+    //make window an auxillary view in fullscreen
+    [window setCollectionBehavior:NSWindowCollectionBehaviorFullScreenAuxiliary];
+
     //set images and text for popup button items
     [self.fLevelButton itemAtIndex:LEVEL_ERROR].title = NSLocalizedString(@"Error", "Message window -> level string");
     [self.fLevelButton itemAtIndex:LEVEL_WARN].title = NSLocalizedString(@"Warn", "Message window -> level string");