allow to use pixmap brushes as brush masks
Submitted by Sven Neumann
Link to original bug (#413826)
Description
Currently pixmap brushes are colored brush stamps and there is no way to change their colors. Internally the brush contains of a pixmap and a mask and one could very well only use the mask so that the brush would behave like a standard brush and paint in the foreground color. It is already possible to do that by abusing the "Pressure Sensitivity: Color" option. But this feature is not very discoverable and it blocks bug #411896.
Version: git master