Add exclusive window handling to DisplayServer (on macOS and Windows).

doc/classes/DisplayServer.xml

@@ -638,6 +638,16 @@
 			<description>
 			</description>
 		</method>
+		<method name="window_set_exclusive">
+			<return type="void" />
+			<argument index="0" name="window_id" type="int" />
+			<argument index="1" name="exclusive" type="bool" />
+			<description>
+				If set to [code]true[/code], this window will always stay on top of its parent window, parent window will ignore input while this window is opened.
+				[b]Note:[/b] On macOS, exclusive windows are confined to the same space (virtual desktop or screen) as the parent window.
+				[b]Note:[/b] This method is implemented on macOS and Windows.
+			</description>
+		</method>
 		<method name="window_set_flag">
 			<return type="void" />
 			<argument index="0" name="flag" type="int" enum="DisplayServer.WindowFlags" />

platform/osx/display_server_osx.h

@@ -95,6 +95,7 @@ public:
 		ObjectID instance_id;
 
 		WindowID transient_parent = INVALID_WINDOW_ID;
+		bool exclusive = false;
 		Set<WindowID> transient_children;
 
 		bool layered_window = false;
@@ -274,6 +275,7 @@ public:
 	virtual void window_set_position(const Point2i &p_position, WindowID p_window = MAIN_WINDOW_ID) override;
 
 	virtual void window_set_transient(WindowID p_window, WindowID p_parent) override;
+	virtual void window_set_exclusive(WindowID p_window, bool p_exclusive) override;
 
 	virtual void window_set_max_size(const Size2i p_size, WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual Size2i window_get_max_size(WindowID p_window = MAIN_WINDOW_ID) const override;

platform/osx/display_server_osx.mm

@@ -1471,6 +1471,24 @@ void DisplayServerOSX::window_set_current_screen(int p_screen, WindowID p_window
 	}
 }
 
+void DisplayServerOSX::window_set_exclusive(WindowID p_window, bool p_exclusive) {
+	_THREAD_SAFE_METHOD_
+	ERR_FAIL_COND(!windows.has(p_window));
+	WindowData &wd = windows[p_window];
+	if (wd.exclusive != p_exclusive) {
+		wd.exclusive = p_exclusive;
+		if (wd.transient_parent != INVALID_WINDOW_ID) {
+			WindowData &wd_parent = windows[wd.transient_parent];
+			if (wd.exclusive) {
+				ERR_FAIL_COND_MSG([[wd_parent.window_object childWindows] count] > 0, "Transient parent has another exclusive child.");
+				[wd_parent.window_object addChildWindow:wd.window_object ordered:NSWindowAbove];
+			} else {
+				[wd_parent.window_object removeChildWindow:wd.window_object];
+			}
+		}
+	}
+}
+
 Point2i DisplayServerOSX::window_get_position(WindowID p_window) const {
 	_THREAD_SAFE_METHOD_
 
@@ -1541,8 +1559,11 @@ void DisplayServerOSX::window_set_transient(WindowID p_window, WindowID p_parent
 
 		wd_window.transient_parent = INVALID_WINDOW_ID;
 		wd_parent.transient_children.erase(p_window);
-
 		[wd_window.window_object setCollectionBehavior:NSWindowCollectionBehaviorFullScreenPrimary];
+
+		if (wd_window.exclusive) {
+			[wd_parent.window_object removeChildWindow:wd_window.window_object];
+		}
 	} else {
 		ERR_FAIL_COND(!windows.has(p_parent));
 		ERR_FAIL_COND_MSG(wd_window.transient_parent != INVALID_WINDOW_ID, "Window already has a transient parent");
@@ -1550,8 +1571,11 @@ void DisplayServerOSX::window_set_transient(WindowID p_window, WindowID p_parent
 
 		wd_window.transient_parent = p_parent;
 		wd_parent.transient_children.insert(p_window);
-
 		[wd_window.window_object setCollectionBehavior:NSWindowCollectionBehaviorFullScreenAuxiliary];
+
+		if (wd_window.exclusive) {
+			[wd_parent.window_object addChildWindow:wd_window.window_object ordered:NSWindowAbove];
+		}
 	}
 }
 

platform/windows/display_server_windows.cpp

@@ -830,6 +830,23 @@ void DisplayServerWindows::window_set_position(const Point2i &p_position, Window
 	_update_real_mouse_position(p_window);
 }
 
+void DisplayServerWindows::window_set_exclusive(WindowID p_window, bool p_exclusive) {
+	_THREAD_SAFE_METHOD_
+	ERR_FAIL_COND(!windows.has(p_window));
+	WindowData &wd = windows[p_window];
+	if (wd.exclusive != p_exclusive) {
+		wd.exclusive = p_exclusive;
+		if (wd.transient_parent != INVALID_WINDOW_ID) {
+			WindowData &wd_parent = windows[wd.transient_parent];
+			if (wd.exclusive) {
+				SetWindowLongPtr(wd.hWnd, GWLP_HWNDPARENT, (LONG_PTR)wd_parent.hWnd);
+			} else {
+				SetWindowLongPtr(wd.hWnd, GWLP_HWNDPARENT, (LONG_PTR) nullptr);
+			}
+		}
+	}
+}
+
 void DisplayServerWindows::window_set_transient(WindowID p_window, WindowID p_parent) {
 	_THREAD_SAFE_METHOD_
 
@@ -852,7 +869,9 @@ void DisplayServerWindows::window_set_transient(WindowID p_window, WindowID p_pa
 		wd_window.transient_parent = INVALID_WINDOW_ID;
 		wd_parent.transient_children.erase(p_window);
 
-		SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR) nullptr);
+		if (wd_window.exclusive) {
+			SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR) nullptr);
+		}
 	} else {
 		ERR_FAIL_COND(!windows.has(p_parent));
 		ERR_FAIL_COND_MSG(wd_window.transient_parent != INVALID_WINDOW_ID, "Window already has a transient parent");
@@ -861,7 +880,9 @@ void DisplayServerWindows::window_set_transient(WindowID p_window, WindowID p_pa
 		wd_window.transient_parent = p_parent;
 		wd_parent.transient_children.insert(p_window);
 
-		SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR)wd_parent.hWnd);
+		if (wd_window.exclusive) {
+			SetWindowLongPtr(wd_window.hWnd, GWLP_HWNDPARENT, (LONG_PTR)wd_parent.hWnd);
+		}
 	}
 }
 

platform/windows/display_server_windows.h

@@ -339,6 +339,7 @@ class DisplayServerWindows : public DisplayServer {
 		bool always_on_top = false;
 		bool no_focus = false;
 		bool window_has_focus = false;
+		bool exclusive = false;
 
 		// Used to transfer data between events using timer.
 		WPARAM saved_wparam;
@@ -499,6 +500,7 @@ public:
 	virtual void window_set_position(const Point2i &p_position, WindowID p_window = MAIN_WINDOW_ID) override;
 
 	virtual void window_set_transient(WindowID p_window, WindowID p_parent) override;
+	virtual void window_set_exclusive(WindowID p_window, bool p_exclusive) override;
 
 	virtual void window_set_max_size(const Size2i p_size, WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual Size2i window_get_max_size(WindowID p_window = MAIN_WINDOW_ID) const override;

scene/main/window.cpp

@@ -254,6 +254,7 @@ void Window::_make_window() {
 #endif
 	DisplayServer::get_singleton()->window_set_title(tr_title, window_id);
 	DisplayServer::get_singleton()->window_attach_instance_id(get_instance_id(), window_id);
+	DisplayServer::get_singleton()->window_set_exclusive(window_id, exclusive);
 
 	_update_window_size();
 
@@ -522,6 +523,10 @@ void Window::set_exclusive(bool p_exclusive) {
 
 	exclusive = p_exclusive;
 
+	if (!embedder && window_id != DisplayServer::INVALID_WINDOW_ID) {
+		DisplayServer::get_singleton()->window_set_exclusive(window_id, exclusive);
+	}
+
 	if (transient_parent) {
 		if (p_exclusive && is_inside_tree() && is_visible()) {
 			ERR_FAIL_COND_MSG(transient_parent->exclusive_child && transient_parent->exclusive_child != this, "Transient parent has another exclusive child.");

servers/display_server.cpp

@@ -204,6 +204,10 @@ void DisplayServer::delete_sub_window(WindowID p_id) {
 	ERR_FAIL_MSG("Sub-windows not supported by this display server.");
 }
 
+void DisplayServer::window_set_exclusive(WindowID p_window, bool p_exclusive) {
+	// Do nothing, if not supported.
+}
+
 void DisplayServer::window_set_mouse_passthrough(const Vector<Vector2> &p_region, WindowID p_window) {
 	ERR_FAIL_MSG("Mouse passthrough not supported by this display server.");
 }
@@ -436,6 +440,7 @@ void DisplayServer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("window_can_draw", "window_id"), &DisplayServer::window_can_draw, DEFVAL(MAIN_WINDOW_ID));
 
 	ClassDB::bind_method(D_METHOD("window_set_transient", "window_id", "parent_window_id"), &DisplayServer::window_set_transient);
+	ClassDB::bind_method(D_METHOD("window_set_exclusive", "window_id", "exclusive"), &DisplayServer::window_set_exclusive);
 
 	ClassDB::bind_method(D_METHOD("window_set_ime_active", "active", "window_id"), &DisplayServer::window_set_ime_active, DEFVAL(MAIN_WINDOW_ID));
 	ClassDB::bind_method(D_METHOD("window_set_ime_position", "position", "window_id"), &DisplayServer::window_set_ime_position, DEFVAL(MAIN_WINDOW_ID));

servers/display_server.h

@@ -277,6 +277,7 @@ public:
 	virtual void window_set_position(const Point2i &p_position, WindowID p_window = MAIN_WINDOW_ID) = 0;
 
 	virtual void window_set_transient(WindowID p_window, WindowID p_parent) = 0;
+	virtual void window_set_exclusive(WindowID p_window, bool p_exclusive);
 
 	virtual void window_set_max_size(const Size2i p_size, WindowID p_window = MAIN_WINDOW_ID) = 0;
 	virtual Size2i window_get_max_size(WindowID p_window = MAIN_WINDOW_ID) const = 0;