When you do something else and track changes and you want to rate it, you need to find your amarok window and rate then. It would be simpler to:

1) show rating in OSD notification ( it can be an option in settings, as mayby not everyone wants this
     and also make osd to dont disappear when mouseover event occur.

2) add stars rating in trayicon context menu and/or tray tooltip, so you can rate it / modify easier.