Comment 2 for bug 681009

I just caught a mistake I made in the patch (it didn't tell the WLabel object that a track was unloaded, so moving the mouse over a previously loaded deck would display the track title again...)

Also, the fix works by catching the enter event and leave event in the WLabel class (so holding the mouse over the label causes it to scroll). This also changes the implementation of the WtrackText and WTrackProperty classes to inform the Wlabel class (that might need review, I'm not sure if it's "ok" to do that).