Redesign the User Interface
Often find myself looking for the right button/feature in Painter due to the fact that most everything looks the same. Everything has the grey/dark grey color with very little to no color indication and there are very few actual "icons" used. This is actually a rather important and serious matter as it puts a lot of strain on my eyes and nerves.
I am sure I am not the only one thinking that way. I love Painter (and Designer) but I really wish time was taken to address the situation and really think the UI through. If anyone has thoughts on this I'd love to have the chime in!
My biggest problem with the UI is when assigning images to the different slots, typically you drop the image onto _the buttons_ below for the associated slots, but at times I forget and attempt to drag the images directly onto the Alpha, Stencil and other image _icons_ displayed above.
To me, it's just more intuitive to drop the images directly onto their associated icons since you can at a glance, tell what image is already assigned (or an X if it's not being used)
It might also be related to how UI works currently, stuff almost seems hidden or moving around. It might be possible to streamline it without removing things.
Mark B Tomlinson commented
In some ways this may seem like a cosmetic exercise but the UI is key to efficient workflow as much and perhaps more so than new features.