It looks like you're new here. If you want to get involved, click one of these buttons!
In V19 it seems that some of the UI backgrounds are hardcoded white, while the text colour changes with Window's theme.
If you switch to a high contrast theme in Windows (white text, black background), BricsCAD now shows white text on a white background, which is not terribly useful.
If background colours are set fixed, the text colour must be too.