why there is no pythonscript insine web browsers?

[bramble]

On Nov 13, 3:07 am, Dennis Lee Bieber <wlfr... at ix.netcom.com> wrote:
> On Mon, 12 Nov 2007 20:07:38 +0200, Timuçin K?z?lay
> <t... at savaskarsitlari.org> declaimed the following in comp.lang.python:
>
> > python support? there is even a vbscript support inside MS-IE but there
> > is no python support. it would be really nice and easy for me to use
> > python instead of javascript to write those ajax scripts.
>
>         Javascript is meant to, basically, control the browser and the
> contents of HTML pages sent to it. [snip] Python can not
> be safely sand-boxed (and the early restricted mode modules have been
> removed for that reason).
>

Why can't it be safely sandboxed?

That is, why not just have a Python interpreter and some safe subset
of the Python standard library run with the browser? I mean, aside
from the work involved with combing out the unneeded or dangerous
parts of the standard lib, it seems like it would be much nicer to
just use Python syntax and modules rather than having to fool around
with Javascript.