Experimental: upon change to playlist, send SIGUSR1 to parent process and branch out to all children to force a playlist refresh
function expand_track(tid)
{
var div = document.getElementById('track_inner_' + tid);
if ( div.style.display == 'block' )
{
div.style.display = 'none';
}
else
{
div.style.display = 'block';
}
}