OpenRA

It bugged me that most widgets are hard-coded to white text (grey when disabled), so with some careful copy-pasting from the LabelWidget code and some adjustments I've successfully changed that for the ButtonWidget and will apply that to other Widgets where possible.
However, I have difficulties with the CheckboxWidget. The text is not a problem, but the check remains white. What do I have to do to change that?

Checkbox depends on 'checkbox-bits' with a field named 'checked'.
Take RA as an example. It has the following in chrome.yaml: The check art itself is in uibits/buttons.png at (0,112).

Ah, I see. I really should have known better than to look at buttons.png with Windows Preview/Paint, which translates transparency to white

Thanks. Lesson learned, I guess...