We develop an Exp environment in which:
- the evaluator may post warning messages which will be displayed
in a special message display.
- users may call the Typol evaluator through a popup menu button.
- windows will display the initial and final environments. These
windows will open by necessity and will close if the source window is
closed.
- users may select a variable name in any display and see all
occurrences in all displays with a special selection.