A correlate of more flexible autosizing, and also potentially of vertical layout sections, would be a “splitter bar” object that divides the layout into separate panes for laying out objects. A new layout object type, the splitter bar is added to a layout like any other object type; horizontal and vertical splitter bars are both supported. The splitter has two notable properties:
(1) Objects on either side use the spitter, rather than the far window edge, as their reference point for anchoring and resizing. The splitter itself can be anchored so as to set its initial position and guide its behavior when the window is resized.
(2) The splitter bar can be specified as “fixed” or “user-draggable,” the latter resulting in user-resizable panes. Minimum sizes can be specified for the panes on either side.