tvision is an interesting idea (thanks for it, I'll put it into my bag of things)

as for implementing text-based edits, I have 2 other ideas:

• use vi, its very programmable and could be compiled with perl and even could be stripped down to just one single file for your purposes; I use this way occasionally
• there exists some thing ctk, curses-based GUI with Tcl, which could be available from Perl with Tcl CPAN module.
  I never tried this, but should work...
  Its not very maintained, but my last attempt to compile it succeeded...