[macOS] Use native window drag for the custom editor title bars.

doc/classes/DisplayServer.xml

@@ -1815,6 +1815,14 @@
 				[b]Warning:[/b] Advanced users only! Adding such a callback to a [Window] node will override its default implementation, which can introduce bugs.
 			</description>
 		</method>
+		<method name="window_start_drag">
+			<return type="void" />
+			<param index="0" name="window_id" type="int" default="0" />
+			<description>
+				Starts a drag operation on the window with the given [param window_id], using the current mouse position. Call this method when handling a mouse button being pressed to simulate a pressed event on the window's title bar. Using this method allows the window to participate in space switching, tiling, and other system features.
+				[b]Note:[/b] This method is implemented only on macOS.
+			</description>
+		</method>
 	</methods>
 	<constants>
 		<constant name="FEATURE_GLOBAL_MENU" value="0" enum="Feature" deprecated="Use [NativeMenu] or [PopupMenu] instead.">
@@ -1895,6 +1903,9 @@
 		<constant name="FEATURE_NATIVE_DIALOG_FILE_EXTRA" value="26" enum="Feature">
 			The display server supports all features of [constant FEATURE_NATIVE_DIALOG_FILE], with the added functionality of Options and native dialog file access to [code]res://[/code] and [code]user://[/code] paths. See [method file_dialog_show] and [method file_dialog_with_options_show]. [b]Windows, macOS, Linux (X11/Wayland)[/b]
 		</constant>
+		<constant name="FEATURE_WINDOW_DRAG" value="27" enum="Feature">
+			The display server supports initiating window drag operation on demand. See [method window_start_drag].
+		</constant>
 		<constant name="MOUSE_MODE_VISIBLE" value="0" enum="MouseMode">
 			Makes the mouse cursor visible if it is hidden.
 		</constant>

editor/gui/editor_title_bar.cpp

@@ -54,8 +54,12 @@ void EditorTitleBar::gui_input(const Ref<InputEvent> &p_event) {
 		if (w) {
 			if (mb->get_button_index() == MouseButton::LEFT) {
 				if (mb->is_pressed()) {
-					click_pos = DisplayServer::get_singleton()->mouse_get_position() - w->get_position();
-					moving = true;
+					if (DisplayServer::get_singleton()->has_feature(DisplayServer::FEATURE_WINDOW_DRAG)) {
+						DisplayServer::get_singleton()->window_start_drag(w->get_window_id());
+					} else {
+						click_pos = DisplayServer::get_singleton()->mouse_get_position() - w->get_position();
+						moving = true;
+					}
 				} else {
 					moving = false;
 				}

platform/macos/display_server_macos.h

@@ -402,6 +402,8 @@ public:
 	virtual bool window_maximize_on_title_dbl_click() const override;
 	virtual bool window_minimize_on_title_dbl_click() const override;
 
+	virtual void window_start_drag(WindowID p_window = MAIN_WINDOW_ID) override;
+
 	virtual void window_set_window_buttons_offset(const Vector2i &p_offset, WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual Vector3i window_get_safe_title_margins(WindowID p_window = MAIN_WINDOW_ID) const override;
 

platform/macos/display_server_macos.mm

@@ -765,6 +765,7 @@ bool DisplayServerMacOS::has_feature(Feature p_feature) const {
 		case FEATURE_SCREEN_CAPTURE:
 		case FEATURE_STATUS_INDICATOR:
 		case FEATURE_NATIVE_HELP:
+		case FEATURE_WINDOW_DRAG:
 			return true;
 		default: {
 		}
@@ -2342,6 +2343,16 @@ bool DisplayServerMacOS::window_minimize_on_title_dbl_click() const {
 	return false;
 }
 
+void DisplayServerMacOS::window_start_drag(WindowID p_window) {
+	_THREAD_SAFE_METHOD_
+
+	ERR_FAIL_COND(!windows.has(p_window));
+	WindowData &wd = windows[p_window];
+
+	NSEvent *event = [NSEvent mouseEventWithType:NSEventTypeLeftMouseDown location:((NSWindow *)wd.window_object).mouseLocationOutsideOfEventStream modifierFlags:0 timestamp:[[NSProcessInfo processInfo] systemUptime] windowNumber:((NSWindow *)wd.window_object).windowNumber context:nil eventNumber:0 clickCount:1 pressure:1.0f];
+	[wd.window_object performWindowDragWithEvent:event];
+}
+
 void DisplayServerMacOS::window_set_window_buttons_offset(const Vector2i &p_offset, WindowID p_window) {
 	_THREAD_SAFE_METHOD_
 

servers/display_server.cpp

@@ -972,6 +972,8 @@ void DisplayServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("window_maximize_on_title_dbl_click"), &DisplayServer::window_maximize_on_title_dbl_click);
 	ClassDB::bind_method(D_METHOD("window_minimize_on_title_dbl_click"), &DisplayServer::window_minimize_on_title_dbl_click);
 
+	ClassDB::bind_method(D_METHOD("window_start_drag", "window_id"), &DisplayServer::window_start_drag, DEFVAL(MAIN_WINDOW_ID));
+
 	ClassDB::bind_method(D_METHOD("ime_get_selection"), &DisplayServer::ime_get_selection);
 	ClassDB::bind_method(D_METHOD("ime_get_text"), &DisplayServer::ime_get_text);
 
@@ -1057,6 +1059,7 @@ void DisplayServer::_bind_methods() {
 	BIND_ENUM_CONSTANT(FEATURE_NATIVE_DIALOG_INPUT);
 	BIND_ENUM_CONSTANT(FEATURE_NATIVE_DIALOG_FILE);
 	BIND_ENUM_CONSTANT(FEATURE_NATIVE_DIALOG_FILE_EXTRA);
+	BIND_ENUM_CONSTANT(FEATURE_WINDOW_DRAG);
 
 	BIND_ENUM_CONSTANT(MOUSE_MODE_VISIBLE);
 	BIND_ENUM_CONSTANT(MOUSE_MODE_HIDDEN);

servers/display_server.h

@@ -153,6 +153,7 @@ public:
 		FEATURE_NATIVE_DIALOG_INPUT,
 		FEATURE_NATIVE_DIALOG_FILE,
 		FEATURE_NATIVE_DIALOG_FILE_EXTRA,
+		FEATURE_WINDOW_DRAG,
 	};
 
 	virtual bool has_feature(Feature p_feature) const = 0;
@@ -490,6 +491,8 @@ public:
 	virtual bool window_maximize_on_title_dbl_click() const { return false; }
 	virtual bool window_minimize_on_title_dbl_click() const { return false; }
 
+	virtual void window_start_drag(WindowID p_window = MAIN_WINDOW_ID) {}
+
 	// necessary for GL focus, may be able to use one of the existing functions for this, not sure yet
 	virtual void gl_window_make_current(DisplayServer::WindowID p_window_id);