xwayland: "Accept" confineTo on InputOnly windows

Of sorts, actually make it confine to the pointer focus, as the
InputOnly window is entirely invisible to xwayland accounting,
we don't have a xwl_window for it.

Signed-off-by: Carlos Garnacho <carlosg@gnome.org>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

hw/xwayland/xwayland.c

@@ -318,6 +318,15 @@ xwl_cursor_confined_to(DeviceIntPtr device,
     }
 
     xwl_window = xwl_window_from_window(window);
+    if (!xwl_window && xwl_seat->focus_window) {
+        /* Allow confining on InputOnly windows, but only if the geometry
+         * is the same than the focus window.
+         */
+        if (window->drawable.class == InputOnly) {
+            DebugF("Confine on InputOnly window, assuming pointer focus\n");
+            xwl_window = xwl_seat->focus_window;
+        }
+    }
     if (!xwl_window)
         return;