[CM] snd: control-panel blocks playback

[Bill Schottstaedt]

Thanks very much for the bug report.  It appears that something
in the control panel is generating such a heavy stream of events
that the background play process never gets to run.  If I force
it to run in the foreground, it gets interrupted a lot.  Closing
the panel turns off this stream of events, so a pending play can
finally run.  I'll have to poke at this...