editable text dialog items

[hall@allegra.att.com (Bob Hall)]

Is there an easy way to get a full-function fred window to
be a dialog item inside another (not necessarily fred-) window?
My goal is to have a class of windows, each of which has a listener
pane (where forms are evaluated in a run-time context specialized to
the containing window).

I know about editable-text-dialog-items, but they don't have the
scroll bars or the minibuffer.  I tried just using the class
fred-window, but I get an error saying all windows must have
NIL containers.

-- Bob