I don't have a dualhead setup to test, but in case you cannot move the mouse pointer out of the monitor borders you have a very easy solution: wrap the mouse to the nearest window corner at the begining of movemouse() (I wrote a patch for this once), then you will always align your windows with the borders of the monitor. If there is a way to not let the mouse pointer going outside of the window area during mousemove (I know you can limit the pointer to a window, but I don't know if you can define a region of the root window) then you could completely remove snap. The only remaining issue would be positioning a window in the barrier between monitors, but this solution could be better than no snaping at all, and not too complicated.
hth, -- - yiyus || JGL .
