using uimenu objects to provide Qt figure window menus

[John W. Eaton]

Some time ago when I asked about deprecating the fltk plotting widget, 
one of the reasons given to delay doing that was that the qt widget does 
not use uimenu objects for the figure menus.  I'd like to fix that but 
would like to have some input from others first.

I see that if I comment out the lines

  ## Only FLTK toolkit currently provides menubar
  if (! strcmp (get (fig, "__graphics_toolkit__"), "fltk"))
    return;
  endif

in scripts/plot/util/private/__add_default_menu__.m, then additional 
"file" and "edit" menus are added to the figure menubar.  These are the 
same as the ones use for the fltk figure window and the actions appear 
to work.  So I think the comment about only the fltk toolkit providing a 
menubar is not correct.  Then it seems that the simplest fix would be to 
eliminate the built-in menus from the qt widget and enable these menu 
items instead.  But then we would lose the "help" menu from the qt 
widget, and the items in the "edit" menu are not the same in the qt and 
fltk widgets, and the qt "edit" menu has icons that are not present in 
the fltk widget.

It would be easy enough to add a help menu for both the qt and fltk 
plotting widgets.

What should we do about the items in the "edit" menu?  I guess it makes 
sense to merge all items so the the qt and fltk widgets have the same set.

What about icons in the uimenu items?  There seems to be no standard 
Matlab way to do that.  Should we add a new "__icon__" property?  Or 
just use the "userdata" property for the icon name?

jwe