do not arbitrarily center "lost" child windows, center them on the parent

if the parent is also lost, it will eventually be rescued and thus all children
will also be saved

 #WeirdCommitLogs

src/bin/e_client.c

@@ -2238,7 +2238,12 @@ e_client_idler_before(void)
             )
           {
              if (e_config->screen_limits != E_CLIENT_OFFSCREEN_LIMIT_ALLOW_FULL)
-               _e_client_move_lost_window_to_center(ec);
+               {
+                  if (ec->parent)
+                    e_comp_object_util_center_on(ec->frame, ec->parent->frame);
+                  else
+                    _e_client_move_lost_window_to_center(ec);
+               }
           }
      }