This class creates an editor frame with the standard menu bar. The
frame and its buffers can be managed by a mred:frame-group%
object (see also 
Frame and Buffer Groups).
After super-init is called, filename is passed to open-file. If group is not #f, then this frame and its buffers are placed under the management of the group. If group is #f and auto-save? is #t, then the frame is registered for autosave callbacks. If show? is #t, then the frame is imediately shown to the user.
The global variable mred:frames is initially #f. It can be modified to designate a default group for standard editor frames.