First of all, a package installer for just an application is a bit overboard. Users are usually weary of packages since it doesn't show what is being installed. I recommend a .zip or a .dmg.

Opening the app shows up a Preferences window. Dismissing the window quits the app. That's odd. There's no way to get rid of this window.

Opening a torrent brings a huge window to front and spits far too much info to the console. Maybe useful in a debug version, but not a release version.

The textured buttons on an aqua background is a no-no, really.