Why does is the cursor colour changed when setting a foreground colour style hint?

[Dannii Willis]

We discovered a little while ago that setting a foreground colour style hint changes the cursor colour, possibly making it invisible: https://github.com/i7/extensions/issues/31

This was fairly easy to work around in Flexible Windows, but I have to wonder why it happens. I took a quick look at the garglk code and it looks like this is by design, but it seems more buggy to me.

Does anyone know why this is the case - are there cases where it makes a lot of sense? And could we document this somewhere? An extra comment in the garglk.ini would probably be the most useful.