1. The hidden line algorithm is not perfect.  The back of the object
can bleed through to the front.  We should put in a option of not
drawing the back at all.

2. The list of available devices is often longer than the length of
a screen.  This output should be sent through a pager.

3. On some devices, such as X11, there can only be one active plotting
window.

4. In the Atari version, windows are not currently supported.  This
means gnuplot 3.4 will not run with MultiAES.  We hope to correct
this shortly in gpcontrb.tar.z.
