I'm sorry I'm not contributing code, and that the following is mac osx specific. and it is only an observation. (and I'm posting it why? because I'm looking for confirmation, maybe, and to point out one possible unexpected advantage of X11 over native.)
there appears to be a difference between handling of X11 windows and native windows regarding what happens when - mouse cursor is in window - you start making a selection with b1 - while making the selection you cross the window border - outside the window you press b2 or b3 to finish the chord with the x11 window everything works as expected, at least on 10.4.11 with the native window the chord is not finished but instead the window under the mouse gets select (or you end up in finder). this seems to be independent of the actual application (acme-sac, 9vx). the non-working with native window I encounter almost every day; that it does work with X I only found minutes ago. regarding 'code, code, code' I was annoyed to the point where I started to wonder whether it would make sense to add something similar to the 'stay in the scroll bar while scrolling' feature, but then to stay in the window while selecting. to my surprise I found it actually working ok with X11 window. Axel.