Use _NET_WM_STATE_FULLSCREEN as a first measure, only falling back to override-redirect when not supported.

gfx/common/x11_common.c

@@ -107,7 +107,48 @@ void x11_show_mouse(Display *dpy, Window win, bool state)
       x11_hide_mouse(dpy, win);
 }
 
-void x11_windowed_fullscreen(Display *dpy, Window win)
+static bool x11_check_atom_supported(Display *dpy, Atom atom)
+{
+   Atom XA_NET_SUPPORTED = XInternAtom(dpy, "_NET_SUPPORTED", True);
+   Atom type;
+   int format;
+   unsigned long nitems;
+   unsigned long bytes_after;
+   Atom *prop;
+   int i;
+
+   if (XA_NET_SUPPORTED == None)
+      return false;
+
+   XGetWindowProperty(dpy, DefaultRootWindow(dpy), XA_NET_SUPPORTED, 0, UINT_MAX, False, XA_ATOM, &type, &format,&nitems, &bytes_after, (unsigned char **) &prop);
+
+   if (!prop || type != XA_ATOM)
+   {
+      return false;
+   }
+
+   for (i = 0; i < nitems; i++)
+   {
+      if (prop[i] == atom)
+      {
+         XFree(prop);
+         return true;
+      }
+   }
+
+   XFree(prop);
+
+   return false;
+}
+
+bool x11_has_net_wm_fullscreen(Display *dpy)
+{
+   XA_NET_WM_STATE_FULLSCREEN = XInternAtom(dpy, "_NET_WM_STATE_FULLSCREEN", False);
+
+   return x11_check_atom_supported(dpy, XA_NET_WM_STATE_FULLSCREEN);
+}
+
+void x11_set_net_wm_fullscreen(Display *dpy, Window win)
 {
    XEvent xev                 = {0};
 

gfx/common/x11_common.h

@@ -29,7 +29,8 @@ extern Colormap g_x11_cmap;
 extern unsigned g_x11_screen;
 
 void x11_show_mouse(Display *dpy, Window win, bool state);
-void x11_windowed_fullscreen(Display *dpy, Window win);
+bool x11_has_net_wm_fullscreen(Display *dpy);
+void x11_set_net_wm_fullscreen(Display *dpy, Window win);
 void x11_suspend_screensaver(Window win, bool enable);
 bool x11_enter_fullscreen(video_frame_info_t *video_info,
       Display *dpy, unsigned width,

gfx/drivers/xvideo.c

@@ -583,7 +583,7 @@ static void *xv_init(const video_info_t *video,
 
    if (video->fullscreen)
    {
-      x11_windowed_fullscreen(g_x11_dpy, g_x11_win);
+      x11_set_net_wm_fullscreen(g_x11_dpy, g_x11_win);
       x11_show_mouse(g_x11_dpy, g_x11_win, false);
    }
 

gfx/drivers_context/x_ctx.c

@@ -37,6 +37,7 @@
 #endif
 
 #include <string/stdstring.h>
+#include <X11/Xatom.h>
 
 #include "../../configuration.h"
 #include "../../frontend/frontend_driver.h"
@@ -678,7 +679,6 @@ static bool gfx_ctx_x_set_video_mode(void *data,
    swa.event_mask = StructureNotifyMask | KeyPressMask | KeyReleaseMask |
       LeaveWindowMask | EnterWindowMask |
       ButtonReleaseMask | ButtonPressMask;
-   swa.override_redirect = fullscreen ? True : False;
 
    if (fullscreen && !windowed_full)
    {
@@ -691,6 +691,8 @@ static bool gfx_ctx_x_set_video_mode(void *data,
          RARCH_ERR("[GLX]: Entering true fullscreen failed. Will attempt windowed mode.\n");
    }
 
+   swa.override_redirect = (!x11_has_net_wm_fullscreen(g_x11_dpy) && true_full) ? True : False;
+
    if (video_info->monitor_index)
       g_x11_screen = video_info->monitor_index - 1;
 
@@ -721,7 +723,7 @@ static bool gfx_ctx_x_set_video_mode(void *data,
          x_off, y_off, width, height, 0,
          vi->depth, InputOutput, vi->visual,
          CWBorderPixel | CWColormap | CWEventMask |
-         (true_full ? CWOverrideRedirect : 0), &swa);
+         CWOverrideRedirect, &swa);
    XSetWindowBackground(g_x11_dpy, g_x11_win, 0);
 
    XChangeProperty(g_x11_dpy, g_x11_win, net_wm_icon, cardinal, 32, PropModeReplace, (const unsigned char*)retroarch_icon_data, sizeof(retroarch_icon_data) / sizeof(*retroarch_icon_data));
@@ -778,6 +780,8 @@ static bool gfx_ctx_x_set_video_mode(void *data,
    {
       RARCH_LOG("[GLX]: Using true fullscreen.\n");
       XMapRaised(g_x11_dpy, g_x11_win);
+      if (swa.override_redirect == False)
+         x11_set_net_wm_fullscreen(g_x11_dpy, g_x11_win);
    }
    else if (fullscreen)
    {
@@ -792,7 +796,7 @@ static bool gfx_ctx_x_set_video_mode(void *data,
        * x_off and y_off usually get ignored in XCreateWindow().
        */
       x11_move_window(g_x11_dpy, g_x11_win, x_off, y_off, width, height);
-      x11_windowed_fullscreen(g_x11_dpy, g_x11_win);
+      x11_set_net_wm_fullscreen(g_x11_dpy, g_x11_win);
    }
    else
    {

gfx/drivers_context/xegl_ctx.c

@@ -297,7 +297,6 @@ static bool gfx_ctx_xegl_set_video_mode(void *data,
          vi->visual, AllocNone);
    swa.event_mask = StructureNotifyMask | KeyPressMask |
       ButtonPressMask | ButtonReleaseMask | KeyReleaseMask;
-   swa.override_redirect = fullscreen ? True : False;
 
    if (fullscreen && !video_info->windowed_fullscreen)
    {
@@ -310,6 +309,8 @@ static bool gfx_ctx_xegl_set_video_mode(void *data,
          RARCH_ERR("[X/EGL]: Entering true fullscreen failed. Will attempt windowed mode.\n");
    }
 
+   swa.override_redirect = (!x11_has_net_wm_fullscreen(g_x11_dpy) && true_full) ? True : False;
+
    if (video_info->monitor_index)
       g_x11_screen = video_info->monitor_index - 1;
 
@@ -340,7 +341,7 @@ static bool gfx_ctx_xegl_set_video_mode(void *data,
          x_off, y_off, width, height, 0,
          vi->depth, InputOutput, vi->visual,
          CWBorderPixel | CWColormap | CWEventMask |
-         (true_full ? CWOverrideRedirect : 0), &swa);
+         CWOverrideRedirect, &swa);
    XSetWindowBackground(g_x11_dpy, g_x11_win, 0);
 
    if (fullscreen && config_get_ptr()->bools.video_disable_composition)
@@ -372,6 +373,8 @@ static bool gfx_ctx_xegl_set_video_mode(void *data,
    {
       RARCH_LOG("[X/EGL]: Using true fullscreen.\n");
       XMapRaised(g_x11_dpy, g_x11_win);
+      if (swa.override_redirect == False)
+         x11_set_net_wm_fullscreen(g_x11_dpy, g_x11_win);
    }
    else if (fullscreen)
    {
@@ -385,7 +388,7 @@ static bool gfx_ctx_xegl_set_video_mode(void *data,
        * x_off and y_off usually get ignored in XCreateWindow().
        */
       x11_move_window(g_x11_dpy, g_x11_win, x_off, y_off, width, height);
-      x11_windowed_fullscreen(g_x11_dpy, g_x11_win);
+      x11_set_net_wm_fullscreen(g_x11_dpy, g_x11_win);
    }
    else
    {