Thank you, jgpaiva, for a fantastic application -- I can't live without it now
Keep up the good work!
In case anyone is interested, I made this grid with these features:
1. All combinations of 2 columns x 2 rows and 3 columns x 2 rows.
2. 2-monitor support (add 30 to trigger codes for 2nd monitor).
3. Trigger codes corresponding to numeric keypad key positions.
4. Most popular standard sizes according to http://store.steampowered.com/hwsurvey/
(1024x768 [trigger 40], 1280x1024 , 1440x900  and 1680x1050 ) for Web development.
5a. 2-column windows vertically inset by 1 pixel so that 3-column windows can be focused by moving the mouse pointer to the left/right screen edge and clicking.
5b. 3-column windows horizontally inset by 1 pixel so that 2-column windows can be focused by moving the mouse pointer to the top/bottom screen edge and clicking.
I find feature #5 really useful as I can use muscle memory and needn't depend on the taskbar (and Alt+Tab) to select windows.
P.S. Is that a way to label the trigger areas with descriptions when the grid is shown, similar to "On Top" and "Undo"?