2 files changed, 27 insertions, 8 deletions

diff --git a/platform/linuxbsd/x11/display_server_x11.cpp b/platform/linuxbsd/x11/display_server_x11.cpp
index ec6947e180..9af2206015 100644
--- a/platform/linuxbsd/x11/display_server_x11.cpp
+++ b/platform/linuxbsd/x11/display_server_x11.cpp
@@ -1582,7 +1582,7 @@ void DisplayServerX11::_update_size_hints(WindowID p_window) {
 	xsh->width = wd.size.width;
 	xsh->height = wd.size.height;
 
-	if (window_mode == WINDOW_MODE_FULLSCREEN) {
+	if (window_mode == WINDOW_MODE_FULLSCREEN || window_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
 		// Do not set any other hints to prevent the window manager from ignoring the fullscreen flags
 	} else if (window_get_flag(WINDOW_FLAG_RESIZE_DISABLED, p_window)) {
 		// If resizing is disabled, use the forced size
@@ -1949,7 +1949,7 @@ void DisplayServerX11::_validate_mode_on_map(WindowID p_window) {
 	// Check if we applied any window modes that didn't take effect while unmapped
 	const WindowData &wd = windows[p_window];
 	if (wd.fullscreen && !_window_fullscreen_check(p_window)) {
-		_set_wm_fullscreen(p_window, true);
+		_set_wm_fullscreen(p_window, true, wd.exclusive_fullscreen);
 	} else if (wd.maximized && !_window_maximize_check(p_window, "_NET_WM_STATE")) {
 		_set_wm_maximized(p_window, true);
 	} else if (wd.minimized && !_window_minimize_check(p_window)) {
@@ -2024,7 +2024,7 @@ void DisplayServerX11::_set_wm_minimized(WindowID p_window, bool p_enabled) {
 	wd.minimized = p_enabled;
 }
 
-void DisplayServerX11::_set_wm_fullscreen(WindowID p_window, bool p_enabled) {
+void DisplayServerX11::_set_wm_fullscreen(WindowID p_window, bool p_enabled, bool p_exclusive) {
 	ERR_FAIL_COND(!windows.has(p_window));
 	WindowData &wd = windows[p_window];
 
@@ -2063,7 +2063,14 @@ void DisplayServerX11::_set_wm_fullscreen(WindowID p_window, bool p_enabled) {
 
 	// set bypass compositor hint
 	Atom bypass_compositor = XInternAtom(x11_display, "_NET_WM_BYPASS_COMPOSITOR", False);
-	unsigned long compositing_disable_on = p_enabled ? 1 : 0;
+	unsigned long compositing_disable_on = 0; // Use default.
+	if (p_enabled) {
+		if (p_exclusive) {
+			compositing_disable_on = 1; // Force composition OFF to reduce overhead.
+		} else {
+			compositing_disable_on = 2; // Force composition ON to allow popup windows.
+		}
+	}
 	if (bypass_compositor != None) {
 		XChangeProperty(x11_display, wd.x11_window, bypass_compositor, XA_CARDINAL, 32, PropModeReplace, (unsigned char *)&compositing_disable_on, 1);
 	}
@@ -2109,8 +2116,9 @@ void DisplayServerX11::window_set_mode(WindowMode p_mode, WindowID p_window) {
 		case WINDOW_MODE_FULLSCREEN: {
 			//Remove full-screen
 			wd.fullscreen = false;
+			wd.exclusive_fullscreen = false;
 
-			_set_wm_fullscreen(p_window, false);
+			_set_wm_fullscreen(p_window, false, false);
 
 			//un-maximize required for always on top
 			bool on_top = window_get_flag(WINDOW_FLAG_ALWAYS_ON_TOP, p_window);
@@ -2143,7 +2151,13 @@ void DisplayServerX11::window_set_mode(WindowMode p_mode, WindowID p_window) {
 			}
 
 			wd.fullscreen = true;
-			_set_wm_fullscreen(p_window, true);
+			if (p_mode == WINDOW_MODE_EXCLUSIVE_FULLSCREEN) {
+				wd.exclusive_fullscreen = true;
+				_set_wm_fullscreen(p_window, true, true);
+			} else {
+				wd.exclusive_fullscreen = false;
+				_set_wm_fullscreen(p_window, true, false);
+			}
 		} break;
 		case WINDOW_MODE_MAXIMIZED: {
 			_set_wm_maximized(p_window, true);
@@ -2158,7 +2172,11 @@ DisplayServer::WindowMode DisplayServerX11::window_get_mode(WindowID p_window) c
 	const WindowData &wd = windows[p_window];
 
 	if (wd.fullscreen) { //if fullscreen, it's not in another mode
-		return WINDOW_MODE_FULLSCREEN;
+		if (wd.exclusive_fullscreen) {
+			return WINDOW_MODE_EXCLUSIVE_FULLSCREEN;
+		} else {
+			return WINDOW_MODE_FULLSCREEN;
+		}
 	}
 
 	// Test maximized.
diff --git a/platform/linuxbsd/x11/display_server_x11.h b/platform/linuxbsd/x11/display_server_x11.h
index c88a6b466a..1e510d4564 100644
--- a/platform/linuxbsd/x11/display_server_x11.h
+++ b/platform/linuxbsd/x11/display_server_x11.h
@@ -159,6 +159,7 @@ class DisplayServerX11 : public DisplayServer {
 		//better to guess on the fly, given WM can change it
 		//WindowMode mode;
 		bool fullscreen = false; //OS can't exit from this mode
+		bool exclusive_fullscreen = false;
 		bool on_top = false;
 		bool borderless = false;
 		bool resize_disabled = false;
@@ -283,7 +284,7 @@ class DisplayServerX11 : public DisplayServer {
 	bool _window_minimize_check(WindowID p_window) const;
 	void _validate_mode_on_map(WindowID p_window);
 	void _update_size_hints(WindowID p_window);
-	void _set_wm_fullscreen(WindowID p_window, bool p_enabled);
+	void _set_wm_fullscreen(WindowID p_window, bool p_enabled, bool p_exclusive);
 	void _set_wm_maximized(WindowID p_window, bool p_enabled);
 	void _set_wm_minimized(WindowID p_window, bool p_enabled);