Hello,
I got this strange thing that occasionally the combination of the ALT key produces a black stroke instead of Zsub. I don’t know when this changes while I’m working - is it a bug or a shortcut I’m using beeing not aware of.
This happens mostly with the CLAY brush - when it appears then other brushes still work fine with the ALT key as Zsub.
What should I do or what should I click to reset the Brush setting?
any help is appreciated!
BTW: I tried to search the forums and didn’t find a similar problem - either I used the wrong keywords or this is a noob problem 
EDIT: Problem solved!
Seems I found the moste simple answer - I propably activated the shortcut for polypaint somehow…