Implement a transient_to_focused mode

This intends to be the correct way to handle non-child windows becoming covered by the current window when becoming focused.
Enabling this property on select windows, they will become transient to the currently focused one when becoming visible.

This deprecates the "unparent_when_invisible" function introduced by #76025.

doc/classes/Window.xml

@@ -668,6 +668,9 @@
 			If [code]true[/code], the [Window] is transient, i.e. it's considered a child of another [Window]. The transient window will be destroyed with its transient parent and will return focus to their parent when closed. The transient window is displayed on top of a non-exclusive full-screen parent window. Transient windows can't enter full-screen mode.
 			Note that behavior might be different depending on the platform.
 		</member>
+		<member name="transient_to_focused" type="bool" setter="set_transient_to_focused" getter="is_transient_to_focused" default="false">
+			If [code]true[/code], and the [Window] is [member transient], this window will (at the time of becoming visible) become transient to the currently focused window instead of the immediate parent window in the hierarchy. Note that the transient parent is assigned at the time this window becomes visible, so changing it afterwards has no effect until re-shown.
+		</member>
 		<member name="transparent" type="bool" setter="set_flag" getter="get_flag" default="false">
 			If [code]true[/code], the [Window]'s background can be transparent. This is best used with embedded windows.
 			[b]Note:[/b] Transparency support is implemented on Linux, macOS and Windows, but availability might vary depending on GPU driver, display manager, and compositor capabilities.

editor/editor_node.cpp

@@ -7803,6 +7803,7 @@ EditorNode::EditorNode() {
 	file = memnew(EditorFileDialog);
 	gui_base->add_child(file);
 	file->set_current_dir("res://");
+	file->set_transient_to_focused(true);
 
 	file_export_lib = memnew(EditorFileDialog);
 	file_export_lib->set_title(TTR("Export Library"));

platform/linuxbsd/x11/display_server_x11.cpp

@@ -2891,10 +2891,15 @@ void DisplayServerX11::window_move_to_foreground(WindowID p_window) {
 	XFlush(x11_display);
 }
 
+DisplayServerX11::WindowID DisplayServerX11::get_focused_window() const {
+	return last_focused_window;
+}
+
 bool DisplayServerX11::window_is_focused(WindowID p_window) const {
 	_THREAD_SAFE_METHOD_
 
 	ERR_FAIL_COND_V(!windows.has(p_window), false);
+
 	const WindowData &wd = windows[p_window];
 
 	return wd.focused;

platform/linuxbsd/x11/display_server_x11.h

@@ -491,6 +491,8 @@ public:
 	virtual void window_move_to_foreground(WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual bool window_is_focused(WindowID p_window = MAIN_WINDOW_ID) const override;
 
+	virtual WindowID get_focused_window() const override;
+
 	virtual bool window_can_draw(WindowID p_window = MAIN_WINDOW_ID) const override;
 
 	virtual bool can_any_window_draw() const override;

platform/macos/display_server_macos.h

@@ -428,6 +428,8 @@ public:
 	virtual void window_move_to_foreground(WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual bool window_is_focused(WindowID p_window = MAIN_WINDOW_ID) const override;
 
+	virtual WindowID get_focused_window() const override;
+
 	virtual bool window_can_draw(WindowID p_window = MAIN_WINDOW_ID) const override;
 
 	virtual bool can_any_window_draw() const override;

platform/macos/display_server_macos.mm

@@ -3723,6 +3723,10 @@ bool DisplayServerMacOS::window_is_focused(WindowID p_window) const {
 	return wd.focused;
 }
 
+DisplayServerMacOS::WindowID DisplayServerMacOS::get_focused_window() const {
+	return last_focused_window;
+}
+
 bool DisplayServerMacOS::window_can_draw(WindowID p_window) const {
 	return windows[p_window].is_visible;
 }

platform/windows/display_server_windows.cpp

@@ -1916,6 +1916,10 @@ bool DisplayServerWindows::window_is_focused(WindowID p_window) const {
 	return wd.window_focused;
 }
 
+DisplayServerWindows::WindowID DisplayServerWindows::get_focused_window() const {
+	return last_focused_window;
+}
+
 bool DisplayServerWindows::window_can_draw(WindowID p_window) const {
 	_THREAD_SAFE_METHOD_
 

platform/windows/display_server_windows.h

@@ -611,6 +611,8 @@ public:
 	virtual void window_move_to_foreground(WindowID p_window = MAIN_WINDOW_ID) override;
 	virtual bool window_is_focused(WindowID p_window = MAIN_WINDOW_ID) const override;
 
+	virtual WindowID get_focused_window() const override;
+
 	virtual bool window_can_draw(WindowID p_window = MAIN_WINDOW_ID) const override;
 
 	virtual bool can_any_window_draw() const override;

scene/main/window.cpp

@@ -573,6 +573,10 @@ bool Window::is_in_edited_scene_root() const {
 void Window::_make_window() {
 	ERR_FAIL_COND(window_id != DisplayServer::INVALID_WINDOW_ID);
 
+	if (transient && transient_to_focused) {
+		_make_transient();
+	}
+
 	uint32_t f = 0;
 	for (int i = 0; i < FLAG_MAX; i++) {
 		if (flags[i]) {
@@ -665,6 +669,10 @@ void Window::_clear_window() {
 
 	_update_viewport_size();
 	RS::get_singleton()->viewport_set_update_mode(get_viewport_rid(), RS::VIEWPORT_UPDATE_DISABLED);
+
+	if (transient && transient_to_focused) {
+		_clear_transient();
+	}
 }
 
 void Window::_rect_changed_callback(const Rect2i &p_callback) {
@@ -864,18 +872,29 @@ void Window::_make_transient() {
 		return;
 	}
 	//find transient parent
-	Viewport *vp = get_parent()->get_viewport();
-	Window *window = nullptr;
-	while (vp) {
-		window = Object::cast_to<Window>(vp);
-		if (window) {
-			break;
-		}
-		if (!vp->get_parent()) {
-			break;
-		}
 
-		vp = vp->get_parent()->get_viewport();
+	Window *window = nullptr;
+
+	if (!is_embedded() && transient_to_focused) {
+		DisplayServer::WindowID focused_window_id = DisplayServer::get_singleton()->get_focused_window();
+		if (focused_window_id != DisplayServer::INVALID_WINDOW_ID) {
+			window = Object::cast_to<Window>(ObjectDB::get_instance(DisplayServer::get_singleton()->window_get_attached_instance_id(focused_window_id)));
+		}
+	}
+
+	if (!window) {
+		Viewport *vp = get_parent()->get_viewport();
+		while (vp) {
+			window = Object::cast_to<Window>(vp);
+			if (window) {
+				break;
+			}
+			if (!vp->get_parent()) {
+				break;
+			}
+
+			vp = vp->get_parent()->get_viewport();
+		}
 	}
 
 	if (window) {
@@ -919,17 +938,32 @@ void Window::set_transient(bool p_transient) {
 	}
 
 	if (transient) {
-		_make_transient();
+		if (!transient_to_focused) {
+			_make_transient();
+		}
 	} else {
 		_clear_transient();
 	}
 }
 
 bool Window::is_transient() const {
-	ERR_READ_THREAD_GUARD_V(false);
 	return transient;
 }
 
+void Window::set_transient_to_focused(bool p_transient_to_focused) {
+	ERR_MAIN_THREAD_GUARD;
+	if (transient_to_focused == p_transient_to_focused) {
+		return;
+	}
+
+	transient_to_focused = p_transient_to_focused;
+}
+
+bool Window::is_transient_to_focused() const {
+	ERR_READ_THREAD_GUARD_V(false);
+	return transient_to_focused;
+}
+
 void Window::set_exclusive(bool p_exclusive) {
 	ERR_MAIN_THREAD_GUARD;
 	if (exclusive == p_exclusive) {
@@ -1259,7 +1293,7 @@ void Window::_notification(int p_what) {
 				}
 			}
 
-			if (transient) {
+			if (transient && !transient_to_focused) {
 				_make_transient();
 			}
 			if (visible) {
@@ -2753,6 +2787,9 @@ void Window::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_transient", "transient"), &Window::set_transient);
 	ClassDB::bind_method(D_METHOD("is_transient"), &Window::is_transient);
 
+	ClassDB::bind_method(D_METHOD("set_transient_to_focused", "enable"), &Window::set_transient_to_focused);
+	ClassDB::bind_method(D_METHOD("is_transient_to_focused"), &Window::is_transient_to_focused);
+
 	ClassDB::bind_method(D_METHOD("set_exclusive", "exclusive"), &Window::set_exclusive);
 	ClassDB::bind_method(D_METHOD("is_exclusive"), &Window::is_exclusive);
 
@@ -2884,6 +2921,7 @@ void Window::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "visible"), "set_visible", "is_visible");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "wrap_controls"), "set_wrap_controls", "is_wrapping_controls");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "transient"), "set_transient", "is_transient");
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "transient_to_focused"), "set_transient_to_focused", "is_transient_to_focused");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "exclusive"), "set_exclusive", "is_exclusive");
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "unresizable"), "set_flag", "get_flag", FLAG_RESIZE_DISABLED);
 	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "borderless"), "set_flag", "get_flag", FLAG_BORDERLESS);

scene/main/window.h

@@ -126,6 +126,7 @@ private:
 
 	bool use_font_oversampling = false;
 	bool transient = false;
+	bool transient_to_focused = false;
 	bool exclusive = false;
 	bool wrap_controls = false;
 	bool updating_child_controls = false;
@@ -313,6 +314,9 @@ public:
 	void set_transient(bool p_transient);
 	bool is_transient() const;
 
+	void set_transient_to_focused(bool p_transient_to_focused);
+	bool is_transient_to_focused() const;
+
 	void set_exclusive(bool p_exclusive);
 	bool is_exclusive() const;
 

servers/display_server.cpp

@@ -596,6 +596,10 @@ DisplayServer::VSyncMode DisplayServer::window_get_vsync_mode(WindowID p_window)
 	return VSyncMode::VSYNC_ENABLED;
 }
 
+DisplayServer::WindowID DisplayServer::get_focused_window() const {
+	return MAIN_WINDOW_ID; // Proper value for single windows.
+}
+
 void DisplayServer::set_context(Context p_context) {
 }
 

servers/display_server.h

@@ -436,6 +436,8 @@ public:
 	virtual void window_move_to_foreground(WindowID p_window = MAIN_WINDOW_ID) = 0;
 	virtual bool window_is_focused(WindowID p_window = MAIN_WINDOW_ID) const = 0;
 
+	virtual WindowID get_focused_window() const;
+
 	virtual void window_set_window_buttons_offset(const Vector2i &p_offset, WindowID p_window = MAIN_WINDOW_ID) {}
 	virtual Vector3i window_get_safe_title_margins(WindowID p_window = MAIN_WINDOW_ID) const { return Vector3i(); }