Currently, pressing tab in edit will add 4 spaces to the text (or fewer to maintain a multiple-of-4 alignment). I think this should be changed to be the tab character. That will make it easier to navigate through the code using only the arrow keys, and will cause mouse clicks to snap more or less to the appropriate multiple-of-4 horizontal position.

ShEdit has supported 4-wide hard tabs for upwards of 3 years, but its other modifications make it kind of slow and painful to use. Feel free to port some of my changes upstream.