diff --git a/video/out/x11_common.c b/video/out/x11_common.c
index b747724b45..bf5113f2de 100644
--- a/video/out/x11_common.c
+++ b/video/out/x11_common.c
@@ -933,8 +933,12 @@ static void vo_x11_sizehint(struct vo *vo, struct mp_rect rc, bool override_pos)
     hint->flags |= PMinSize;
     hint->min_width = hint->min_height = 4;
 
+    // This will use the top/left corner of the window for positioning, instead
+    // of the top/left corner of the client. _NET_MOVERESIZE_WINDOW could be
+    // used to get a different reference point, while keeping gravity.
     hint->flags |= PWinGravity;
     hint->win_gravity = CenterGravity;
+
     XSetWMNormalHints(x11->display, x11->window, hint);
     XFree(hint);
 }