Check Boxes Don't Work Independently

[dhk <dhkuhl optonline net>]

The attached program works but the all the check boxes get checked or
unchecked when only one is clicked.  Sometimes the mouse has to move
accross the rows to refresh the display.  

Can someone explain why this happens and where the mouseover event is
coming from?  If you run the program you'll see what I mean.

Thanks in advance,

--dhk