Several apps I've tried (including my company's app) have scrollbars in the wrong place, inset in the window by one scrollbar width.
Duane Clark has seen this, too, and said "... the scrollbars being in the wrong position in the richtext window? I am pretty sure that is a richtext bug. I see it in every application that uses richtext. For example, run notepad and then resize the window. " (I tried running notepad, and couldn't reproduce it myself, so maybe I'm confused.)
One app that shows the problem is Resource Hunter (free trial download at http://www.boilsoft.com/rchunter.html). Just start it, and look at the position of the scrollbars in the lower left pane.
Is this a well-known problem? I'd like to try fixing it if nobody has a patch yet. Hints welcome. - Dan