We noticed that when pressing ALT+TAB in Windows when playing a game caused the game to minimize and continously loop a section of the sound playing. Would it be possible to mute the sound while the game is minimized?
Also, if in a dialogue, the screen wouldn't redraw until you clicked the mouse (which would cause important messages to disappear...).
Is these things fixable somehow?
Your first bug is on the tracker, so it's a known issue and will be dealt with in due course:
http://www.adventuregamestudio.co.uk/tracker.php?action=detail&id=493
As regards the dialog, do you mean that the problem happens if you alt+tab out of the game and then back in, whilst in a dialog?
Yes.