Enhanced grid - Painting problems on IE6 when moving through the check boxes colum

[Roberto Mosqueda]

The check box cell highlighted by the mouse cursor is painted white on IE6

Instructions to tester:
1.- Open a valid browser
2.- Go to /test_enhanced_grid.html
3.- Select one or more rows
4.- Move the mouse cursor over the check boxes column, as you can see on the image1.gif, the cell selected is painted to white.

As I stated before, this only happens on IE6, on other browsers the cell remains in blue. (see image2.gif to check an example on IE7)

[Adam Peller]

(In [20661]) Patch from Evan. Fix the checkbox painting issue and cell over indicator in IE6. Fixes #10110, #10112 !strict