x11: Don't try to grab the pointer on an unmapped window (thanks, Lee!)

Fixes Bugzilla #5352.

src/video/x11/SDL_x11events.c

@@ -433,8 +433,12 @@ X11_DispatchFocusOut(_THIS, SDL_WindowData *data)
 static void
 X11_DispatchMapNotify(SDL_WindowData *data)
 {
-    SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_RESTORED, 0, 0);
-    SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_SHOWN, 0, 0);
+    SDL_Window *window = data->window;
+    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_RESTORED, 0, 0);
+    SDL_SendWindowEvent(window, SDL_WINDOWEVENT_SHOWN, 0, 0);
+    if (!(window->flags & SDL_WINDOW_HIDDEN) && (window->flags & SDL_WINDOW_INPUT_FOCUS)) {
+        SDL_UpdateWindowGrab(window);
+    }
 }
 
 static void

src/video/x11/SDL_x11window.c

@@ -1576,6 +1576,13 @@ X11_SetWindowGrab(_THIS, SDL_Window * window, SDL_bool grabbed)
     oldstyle_fullscreen = X11_IsWindowLegacyFullscreen(_this, window);
 
     if (oldstyle_fullscreen || grabbed) {
+        /* If the window is unmapped, XGrab calls return GrabNotViewable,
+           so when we get a MapNotify later, we'll try to update the grab as
+           appropriate. */
+        if (window->flags & SDL_WINDOW_HIDDEN) {
+            return;
+        }
+
         /* Try to grab the mouse */
         if (!data->videodata->broken_pointer_grab) {
             const unsigned int mask = ButtonPressMask | ButtonReleaseMask | PointerMotionMask | FocusChangeMask;