Add more flexible gradients
Deluxe Paint had the feature to freehand gradient-filled shapes as opposed to ONLY ellipses and rectangles. You could make blobby or unusual shapes and the gradient filler would accentuate the shape.
This behavior should also be applied to ellipses instead of merely filling them with a radial gradient. The fill should follow the proportions of the ellipse.
Also, in addition to gradient dithering Deluxe Paint had the ability to add a custom amount of random noise to the dithering to produce a rougher or more "natural" texture to the gradient. Could this behavior be reverse engineered or satisfactorily be written from scratch?