This is a demo for twodogs' question at SPF. It is an unobtrusive form enhancement.
Click a TD to toggle it's checkbox. After clicking, drag across other TDs to set their checkboxes to the same value as the clicked one.
Tested on WinXP in Opera 9.10, Firefox 2.0 and IE 7. Tested on Win2K in Opera 7.51 (text selection doesn't cancel), Firefox 1.0.2 and IE 6.