@max - if you call it SplitPanelLite, make it userchrome.js ready, make the code very small, you will have a market
@ed - i just sent him an email, like anyone can from his website contact.. i agree the splitting is not efficient. the current buttons appear all the time on mouseover, are too small one way and too big the other, timeout too fast, cursor should change to a 'hand' pointer. your idea is better but would still have cursors pop up unintended buttons frequently for a very infrequent use.
i'm sticking with the drag and drop button - which i realize can just be one button. if a pane is divided into 9 equal boxes, the middle box on the top/bottom/left/right receives the drop and the split is thus determined. i just don't know how to code it
maybe those optimoz guys might get interested
they figure out stuff like 'offset senstivity from 45° to make a diagonal motion'.