I've been poking around for a way to do this, but maybe I'm just not seeing something simple. When you pull up the pop-up palette, I'd like to be able to move around the positions for some of the icons so they're a tiny bit easier to flick to. This seems like a basic feature of the palette but I'm not seeing any controls to customize positions, so you're stuck with wherever Krita decides to add the brush once it's tagged. Can this be done?

You will need to write code for that, I'm afraid. krita/libs/ui/kis_popup_palette.cpp is the place to start looking.