Embedding game process in editor

doc/classes/DisplayServer.xml

@@ -1883,6 +1883,9 @@
 		<constant name="FEATURE_NATIVE_DIALOG_FILE" value="25" enum="Feature">
 			Display server supports spawning dialogs for selecting files or directories using the operating system's native look-and-feel. See [method file_dialog_show] and [method file_dialog_with_options_show]. [b]Windows, macOS, Linux (X11/Wayland)[/b]
 		</constant>
+		<constant name="FEATURE_WINDOW_EMBEDDING" value="26" enum="Feature">
+			Display server supports embedding a window from another process. [b]Windows, Linux (X11)[/b]
+		</constant>
 		<constant name="MOUSE_MODE_VISIBLE" value="0" enum="MouseMode">
 			Makes the mouse cursor visible if it is hidden.
 		</constant>

doc/classes/Window.xml

@@ -756,6 +756,11 @@
 				Emitted when the mouse cursor leaves the [Window]'s visible area, that is not occluded behind other [Control]s or windows, provided its [member Viewport.gui_disable_input] is [code]false[/code] and regardless if it's currently focused or not.
 			</description>
 		</signal>
+		<signal name="position_changed">
+			<description>
+				Emitted when the [Window] moved.
+			</description>
+		</signal>
 		<signal name="theme_changed">
 			<description>
 				Emitted when the [constant NOTIFICATION_THEME_CHANGED] notification is sent.

editor/editor_run.cpp

@@ -34,6 +34,7 @@
 #include "editor/debugger/editor_debugger_node.h"
 #include "editor/editor_node.h"
 #include "editor/editor_settings.h"
+#include "editor/plugins/game_editor_plugin.h"
 #include "editor/run_instances_dialog.h"
 #include "main/main.h"
 #include "servers/display_server.h"
@@ -175,12 +176,14 @@ Error EditorRun::run(const String &p_scene, const String &p_write_movie) {
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
 			} break;
 			case 3: { // force maximized
+
 				Vector2 pos = screen_rect.position + screen_rect.size / 2;
 				args.push_back("--position");
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
 				args.push_back("--maximized");
 			} break;
 			case 4: { // force fullscreen
+
 				Vector2 pos = screen_rect.position + screen_rect.size / 2;
 				args.push_back("--position");
 				args.push_back(itos(pos.x) + "," + itos(pos.y));
@@ -234,6 +237,9 @@ Error EditorRun::run(const String &p_scene, const String &p_write_movie) {
 		List<String> instance_args(args);
 		RunInstancesDialog::get_singleton()->get_argument_list_for_instance(i, instance_args);
 		RunInstancesDialog::get_singleton()->apply_custom_features(i);
+		if (GameEditor::get_singleton()) {
+			GameEditor::get_singleton()->get_argument_list_for_instance(i, instance_args);
+		}
 
 		if (OS::get_singleton()->is_stdout_verbose()) {
 			print_line(vformat("Running: %s", exec));
@@ -286,6 +292,13 @@ void EditorRun::stop() {
 	running_scene = "";
 }
 
+OS::ProcessID EditorRun::get_current_process() const {
+	if (pids.is_empty()) {
+		return 0;
+	}
+	return pids.get(0);
+}
+
 EditorRun::EditorRun() {
 	status = STATUS_STOP;
 	running_scene = "";

editor/editor_run.h

@@ -32,6 +32,7 @@
 #define EDITOR_RUN_H
 
 #include "core/os/os.h"
+#include "servers/display_server.h"
 
 class EditorRun {
 public:
@@ -58,6 +59,7 @@ class EditorRun {
 	void stop_child_process(OS::ProcessID p_pid);
 	bool has_child_process(OS::ProcessID p_pid) const;
 	int get_child_process_count() const { return pids.size(); }
+	OS::ProcessID get_current_process() const;
 
 	EditorRun();
 };

editor/gui/editor_run_bar.cpp

@@ -293,6 +293,34 @@ void EditorRunBar::play_custom_scene(const String &p_custom) {
 	current_mode = RunMode::RUN_CUSTOM;
 	_run_scene(p_custom);
 }
+void EditorRunBar::restart() {
+	if (!is_playing()) {
+		return;
+	}
+
+	RunMode last_current_mode = current_mode;
+	String last_run_custom_filename = run_custom_filename;
+	String last_run_current_filename = run_current_filename;
+
+	stop_playing();
+
+	switch (last_current_mode) {
+		case RunMode::RUN_MAIN: {
+			_run_scene();
+		} break;
+		case RunMode::RUN_CUSTOM: {
+			play_custom_scene(last_run_custom_filename);
+		} break;
+		case RunMode::RUN_CURRENT: {
+			_run_scene(last_run_current_filename);
+		} break;
+		case RunMode::STOPPED: {
+			// Nothing to do.
+		} break;
+	}
+
+	current_mode = last_current_mode;
+}
 
 void EditorRunBar::stop_playing() {
 	if (editor_run.get_status() == EditorRun::STATUS_STOP) {
@@ -345,6 +373,10 @@ void EditorRunBar::stop_child_process(OS::ProcessID p_pid) {
 	}
 }
 
+OS::ProcessID EditorRunBar::get_current_process() const {
+	return editor_run.get_current_process();
+}
+
 void EditorRunBar::set_movie_maker_enabled(bool p_enabled) {
 	write_movie_button->set_pressed(p_enabled);
 }

editor/gui/editor_run_bar.h

@@ -96,6 +96,7 @@ class EditorRunBar : public MarginContainer {
 	void play_main_scene(bool p_from_native = false);
 	void play_current_scene(bool p_reload = false);
 	void play_custom_scene(const String &p_custom);
+	void restart();
 
 	void stop_playing();
 	bool is_playing() const;
@@ -105,6 +106,7 @@ class EditorRunBar : public MarginContainer {
 
 	OS::ProcessID has_child_process(OS::ProcessID p_pid) const;
 	void stop_child_process(OS::ProcessID p_pid);
+	OS::ProcessID get_current_process() const;
 
 	void set_movie_maker_enabled(bool p_enabled);
 	bool is_movie_maker_enabled() const;