The recoloring code of Blender is a theming nightmare. We have yet another theming problem with black icons at mouse over.

This is a much more general problem than thought. It's coloring the icons at all that is a issue here. In Blender 2.79 the icons did not receive any coloring from the theme at all. Just the text was colored. And this strikes back here.
I have to dive into the C code here. Maybe we find a solution to exclude the coloring of the icons again. Fingers crossed that i find the bit here, and that removing it doesn't make things even worse.

Okay, the simplest way is to change the definition of the icons. Normal icons are affected by coloring. But there is also
And they all gets treaten different in different situations.
We need to check here anyways. Currently all our icons are all DEF_ICON. And this icon type gets colored. The for us interesting type is DEF_ICON_COLOR. Going through UI_icons.h now ...
This also fixes the brightness issue. Above, the old icons with DEF_ICON, below icons with DEF_ICON_COLOR. Searching for the brightness issue. I think Draise had reported it.

Fixed in master
Much better now.
