x11: Fix pointer warp on XWayland

XWayland seems to require that the pointer be hidden when it is warped, so hide and show the pointer when warping, if required.

Note that XWayland still only allows warping within the window, so attempts to warp to global coordinates outside the window won't work.

src/video/x11/SDL_x11mouse.c

@@ -318,6 +318,17 @@ static void X11_WarpMouseInternal(Window xwindow, float x, float y)
 {
     SDL_VideoData *videodata = SDL_GetVideoDevice()->driverdata;
     Display *display = videodata->display;
+    SDL_Mouse *mouse = SDL_GetMouse();
+    SDL_bool warp_hack = SDL_FALSE;
+
+    /* XWayland will only warp the cursor if it is hidden, so this workaround is required. */
+    if (videodata->is_xwayland && mouse && mouse->cursor_shown) {
+        warp_hack = SDL_TRUE;
+    }
+
+    if (warp_hack) {
+        X11_ShowCursor(NULL);
+    }
 #ifdef SDL_VIDEO_DRIVER_X11_XINPUT2
     int deviceid = 0;
     if (X11_Xinput2IsInitialized()) {
@@ -336,6 +347,10 @@ static void X11_WarpMouseInternal(Window xwindow, float x, float y)
     {
         X11_XWarpPointer(display, None, xwindow, 0, 0, 0, 0, (int)x, (int)y);
     }
+
+    if (warp_hack) {
+        X11_ShowCursor(SDL_GetCursor());
+    }
     X11_XSync(display, False);
     videodata->global_mouse_changed = SDL_TRUE;
 }

src/video/x11/SDL_x11video.c

@@ -289,8 +289,10 @@ static SDL_VideoDevice *X11_CreateDevice(void)
     device->device_caps = VIDEO_DEVICE_CAPS_HAS_POPUP_WINDOW_SUPPORT |
                           VIDEO_DEVICE_CAPS_SENDS_FULLSCREEN_DIMENSIONS;
 
-    if (X11_IsXWayland(x11_display))
+    data->is_xwayland = X11_IsXWayland(x11_display);
+    if (data->is_xwayland) {
         device->device_caps |= VIDEO_DEVICE_CAPS_MODE_SWITCHING_EMULATED;
+    }
 
     return device;
 }

src/video/x11/SDL_x11video.h

@@ -133,6 +133,8 @@ struct SDL_VideoData
     SDL_bool is_steam_deck;
     SDL_bool steam_keyboard_open;
 
+    SDL_bool is_xwayland;
+
 };
 
 extern SDL_bool X11_UseDirectColorVisuals(void);