xwayland: ignore pointer focus changes

This reflects what i3 does [1].

[1]: b3faf9fca9/src/handlers.c (L1076)

Fixes: c067fbc010 ("xwm: allow applications to change focus between their own surfaces")
Closes: https://github.com/swaywm/sway/issues/4926
(cherry picked from commit 68820d6c3d)

xwayland/xwm.c

@@ -1231,6 +1231,10 @@ static void xwm_handle_focus_in(struct wlr_xwm *xwm,
 			ev->mode == XCB_NOTIFY_MODE_UNGRAB) {
 		return;
 	}
+	// Ignore pointer focus change events
+	if (ev->detail == XCB_NOTIFY_DETAIL_POINTER) {
+		return;
+	}
 
 	// Do not let X clients change the focus behind the compositor's
 	// back. Reset the focus to the old one if it changed.