When the applet is opened you can press the following keys to control it:
* Space (and K): Play/Pause
* P: Previous song
* N: Next song
* S: Stop playback
* Left key (or J): seek back 5s
* Right key (or L): seek forward 5s
* Home: Go to beginning of track
* End: Go to end of track (ie. basically goes to next track)
* 0..9: Jump to 0%, 10%, 20%, etc of track's length depending on the number

Of course there's still the global shortcuts so you don't actually need this.
While at it I made the slider a bit more reliable while manipulating it so it
wouldn't twitch around.

BUG: 351146
FIXED-IN: 5.6.0