There are 4 error-messages which will be shown together
with the command in the default CON:-window:
 1: wrong number of arguments
 2: wrong arguments
 3: unknown command
 4: command failed

Most of the commands are valid everywhere, but there are exeptions,
e.g. if you haven't defined any variable you can't open
the envelope-window. This would cause error 4.

Normally you can access all program functions without opening
any of the windows, but there are the following exceptions:
 -Timecodes-, AnimInfo-, Envelope- and EnvelopeAdvanced-commands
  require that the corresponding Window was opened
  (This is due the internal data-structure and no error or
   similar.)

If the program executes an ARexx-command all requesters
except the one invoked by the "M_MESSAGE"-command are
turned off, but the requester-messages are shown in the
Log-Window.