Area Manager: revised how an area subdivision gets managed. Originally the 'spacedata' would store regiondata too, but this already became impractical (like having view2d data in region is useful). So I left that part how it is. See new diagram: http://wiki.blender.org/index.php/BlenderDev/Blender2.5/AreaManager This means that regions in an Area define location/size or constraints for how they get arranged. The "RegionType" which is linked to this defines its functionality. For fun, test, and code validation: two temporary hotkeys added. SKEY: splits current region horizontally SHIFT+S: splits vertically Note - in outliner - that "context" sticks to the Area as whole, the region here only defines view. That's the purpose. :) For two outliners with different context you open 2 areas. Also note that dragging screen-edges shows the region-alignment type (split with percentage).