Always on Top is a nice idea I can probably implement!
I almost went with Shift+Shortcut keys originally, but decided it was a bit annoying dealing with key combinations, so I picked the F-keys for simplicity heh. I had only briefly considered that the user might run into the issue of pressing those keys when Pixel Picker was not the current focused window. I'll look into fixing things so the F1-F3 are global instead of dependent on PP having the focus!