+ step *= (key == KSYM_Page_Up ? -1 : +1);
+ element_shift += step * ED_ELEMENTLIST_BUTTONS_HORIZ;
+
+ if (element_shift < 0)
+ element_shift = 0;
+ if (element_shift > num_editor_elements - ED_NUM_ELEMENTLIST_BUTTONS)
+ element_shift = num_editor_elements - ED_NUM_ELEMENTLIST_BUTTONS;
+
+ ModifyGadget(level_editor_gadget[GADGET_ID_SCROLL_LIST_VERTICAL],
+ GDI_SCROLLBAR_ITEM_POSITION,
+ element_shift / ED_ELEMENTLIST_BUTTONS_HORIZ, GDI_END);
+
+ ModifyEditorElementList();
+