tween the OpenGL and zbuffer renderers.
      Params        Creates a dialog box to ask for timing parameters:
         Skip  (default: 1 frms) # frames to advance btw frames.
         Slow  (default: 0 msec) # msec to pause btw frame advances.
         Fs    (default: 1 Hz  ) temporal sampling rate

   Left clicking over the data plots the time-series for the clicked
   pixel in the lower axes.  Double click on the time-series axes
   background to clear them.

   Left click and drag the time cursor on the