Praise, Request, and a Bug Rated 4 out of 5 stars

Praise: Very nice theme -- perfectly minimal. (+6 stars)

Request: When condensing menu to one item, it would be great if I could leave out the bookmarks (commonly used) -- a la TinyMenu's ability to exclude options from the shrinking (-0.5 star)
Also, I don't think you need to put in an extra menu item for the options -- you're not going to change it that much, and you can still get to it via the regular addons option. (-0.5 star)

Bug: I too have an issue where the checkboxes don't show up in Firefox3 (on XP) -- but this only occurs when setting the OS system color option to "dark" -- I'm assuming that your option is making the box forecolor white so it will show up on a dark bg...but the box is still white? (-0.5 star)

I'm also not sure, but I think this addon might crash FF3 when installed with TinyMenu... (-0.5 star)

All in all, the best minimal theme, and I'm probably being too harsh!

This review is for a previous version of the add-on (1.1.3). 

White checkmarks

Thank you for your observation about the white check marks in white check boxes. You are correct that the OS system color option is only to "flip" checkmark colors so that they work on dark backgrounds. Your observation about the white checkmark background was may be helpful in trying to resolve a common complaint.

I have received reports of some conflicts with other addons that have overlapping functionality with Classic Compact Options. I tried to tread lightly to prevent conflicts, but resolving some of takes other addon developers also making a greater effort to tread lightly.

For now my advice is to not use functionality in Classic Compact Options that is covered by another installed addon. Maybe this winter when things slow down for me I'll have time to try and find a way to side step some compatibility issues with other addons.