+ /* Focus the currently focused container on the same level that the
+ * user scrolled on. e.g. the tabbed decoration contains
+ * "urxvt | i3: V[xterm geeqie] | firefox",
+ * focus is on the xterm, but the user scrolled on urxvt.
+ * The splitv container will be focused. */
+ Con *focused = con->parent;
+ focused = TAILQ_FIRST(&(focused->focus_head));
+ con_focus(focused);
+ /* To prevent scrolling from going outside the container (see ticket
+ * #557), we first check if scrolling is possible at all. */
+ bool scroll_prev_possible = (TAILQ_PREV(focused, nodes_head, nodes) != NULL);
+ bool scroll_next_possible = (TAILQ_NEXT(focused, nodes) != NULL);
+ if (event->detail == XCB_BUTTON_INDEX_4 && scroll_prev_possible)