Hi! please add OGG support as mp3 is more and more not being used as mainstream. Melody mania even suggests it as it works best with the engine it uses.
On Widows if you press just "Alt" button in the editor and release it, it is still being treated as pressed. So if you later press some other key e.g. "p" it will be treated as if alt+p was pressed - "Play" menu will be opened instead of activating playback.