One of the basic techniques I teach in watercolors is how to tip the paper and manipulate the paint through gravity.
Since many users of SketchBook are using devices with built-in accelerometers, it would be awesome to have this as a tool feature. That is, the ability to tilt a tablet and have "wet paints" run across the screen.
Also, to have wet colors dropped into a wash of "water" run/bleed through the wet area when the tablet is flat.
And along with this, to mimic real life, the ability to manipulate drying time and degree of wetness, and degree of tilt.
For those on desktop or without accelerometers, the ability to set a gravity point with an anchor point (further away means more tilt possibly?)
An example of gravity used with paint, from the web, is below.
