- Support the command line. So if I double-click a .sty file, it actually opens that file instead of just starting the tool.
- Re-write the retarded "Yes/No/Cancel" message box about importing tiles with different palettes. Nobody can understand it and the confusion can waste epic amounts of time. Such as the way Golden Lap had to be built.
- Maximise and resizing in general should draw sprites in all available space. (You could draw them page-by-page, left-to-right, with a 1px white gap between pages and no gaps between sprites. Or keep the 1px gap between sprites and create a bigger gap between pages where you can put the page number.)
- Scrolling should be vertical, not horizontal.
- Scrollwheel should scroll.
- Inherit XP themes? Buttons don't look like XP buttons, for example.
- Name buttons consistently. "go away!" might be novel to a Slovene weirdo when he's making at app at 4am 6 years ago. But it doesn't make good button text for users, imho.
- Generally make the UI more like Windows, instead of using microscopic text and misaligned controls.
You might find more ideas in old topics on GTA Forums "Old School Modding" area or the Gouranga! Forums "Modding & Editing" area.