Using a browser as a GUI: which Python package

[André]

First, an apology: I realise that I don't know enough about what I am
asking to make sure to use the proper language to phrase my question.

I would like to use a browser (e.g. Firefox) as a simple GUI
"framework".  Note that this is to be done on a single user machine, so
the question of sandboxing is not really relevant here.

The simplest application I would like to start with would be one with
two "windows" (within a browser window) and a single button.  One
window would be used as a Python code editor; the other as an output
window.  On clicking on the button, the code in the editor window would
be run by Python with the result appearing in the output window.

[A more advanced, future version, would be to have Python create some
graphical code (e.g. SVG) that could be passed to the browser to be
displayed within the output window.]

Ideally, I would prefer a Python-based solution only.

My ultimate goal would be to port the main features of two
wxPython-based apps I wrote (rur-ple and Lightning Compiler, both found
at https://sourceforge.net/project/showfiles.php?group_id=125834)
within a standard browser.

Any help/pointers would be appreciated.

André