[CM] track size

[bil at ccrma.Stanford.EDU]

I vaguely remember that it's hard to control the pane
size programmatically.  I tried

(XtVaSetValues ((*motif* 'find-child) (car (sound-widgets 0)) "chn-top")
   (list XmNpaneMinimum 1000))

then XtManage the same widget (it is the xmPanedWidget for
the channel graph), but this had no effect.  The sash moving
code in motif must be able to do this.  I'll poke around.