docview: To make sure TotalSize is > 0
minor code cleanup
New record structure to be used in future OnMove events.
MDI: work area now has a CascadeWindows method.
MDI prototype: fixes code to remove compiler hints
MDI child windows now have a OnMove event
MDI prototype now has basic horizontal scrollbar support.
MDI prototype: demo project now uses the Cascade Windows functionality
MDI: fixed editor settings screwup. Converted Tabs -> Spaces
Merge branch 'mdi_horizontal_scrolling' into develop