The presence or absence of the check marks are not enough?
The only way I know to control the color of the checkboxes and their text labels is to create my own controls/subclass which is not the simplest of tasks.
On Windows it is easier.
-Kirk
I see. I said I didn't know how hard that would be in Cocoa app
To elaborate, the check marks are a good indication, but this would be more visual. I have forgotten few times to mark the box, in hurry. Especially with Graphitte OS X theme where everything is lower contrast anyway.
But if it is not as simple as I though, please put it to the bottom of the drawer - it was just an idea for future interface tweks