I saw you updated the app to fix the dry brush problem. I do not know if this is how it is supposed to work but if I drag the dry brush through paint the brush not only never loses paint but seems to pick up loading the longer you paint the stroke.
What I did: painted a rectangle with a color. Then changed the brush to 0 loading and 0 thinner. I then started a stroke inside the painted part then dragged the stroke all around the non-painted portion of the canvas. It not only never ran out of paint but also seemed to pick up more paint the longer I made the stroke.
The black part is fixed though