winex11: Don't set MWM decorations either for fullscreen virtual desktops.

dlls/winex11.drv/desktop.c

@@ -203,6 +203,11 @@ static BOOL CALLBACK update_windows_on_desktop_resize( HWND hwnd, LPARAM lparam
     return TRUE;
 }
 
+BOOL is_desktop_fullscreen(void)
+{
+    return screen_width == max_width && screen_height == max_height;
+}
+
 static void update_desktop_fullscreen( unsigned int width, unsigned int height)
 {
     Display *display = thread_display();

dlls/winex11.drv/window.c

@@ -1063,7 +1063,8 @@ static void set_mwm_hints( Display *display, struct x11drv_win_data *data, DWORD
 
     if (data->hwnd == GetDesktopWindow())
     {
-        mwm_hints.decorations = MWM_DECOR_TITLE | MWM_DECOR_BORDER | MWM_DECOR_MENU | MWM_DECOR_MINIMIZE;
+        if (is_desktop_fullscreen()) mwm_hints.decorations = 0;
+        else mwm_hints.decorations = MWM_DECOR_TITLE | MWM_DECOR_BORDER | MWM_DECOR_MENU | MWM_DECOR_MINIMIZE;
         mwm_hints.functions        = MWM_FUNC_MOVE | MWM_FUNC_MINIMIZE | MWM_FUNC_CLOSE;
     }
     else

dlls/winex11.drv/x11drv.h

@@ -649,6 +649,7 @@ struct x11drv_mode_info
 
 extern void X11DRV_init_desktop( Window win, unsigned int width, unsigned int height ) DECLSPEC_HIDDEN;
 extern void X11DRV_resize_desktop(unsigned int width, unsigned int height) DECLSPEC_HIDDEN;
+BOOL is_desktop_fullscreen(void) DECLSPEC_HIDDEN;
 extern void X11DRV_Settings_AddDepthModes(void) DECLSPEC_HIDDEN;
 extern void X11DRV_Settings_AddOneMode(unsigned int width, unsigned int height, unsigned int bpp, unsigned int freq) DECLSPEC_HIDDEN;
 unsigned int X11DRV_Settings_GetModeCount(void) DECLSPEC_HIDDEN;