Custom fill area
Create a new option alongside custom draw paths, which is a custom fill area. This suggestion provides the opportunity of dealing with the frantic drawing hand, which is most evident when "drawing" areas. The creation of a fill (reveal) area would be a neat way to allow for fill strategies (like bleed out from a touch point, or 'run down' from top to bottom like paint flowing down the surface. All of these would be creative, but eliminate many of the more unsightly frantic hand movements.