passive Copy-and-Paste with scripts

Hello,

I have written a little note to explain my ideas that could enable a 
safe copy-and-paste in scripts running within web-pages. Please find it 
here:

    http://www.activemath.org/~paul/tmp/Ideal-Browser-Behaviour.html

this follows discussions that happened earlier on this forum and I would 
love to have comments. I still believe that the proposed handlers are 
appropriate and safe. The recent addition is to add a simplistic 
"onselected" handler to enable, in some pages, only "well-formed" 
selections... this is maybe half-baked but complete the requirements 
that I would have for formulae copy-and-paste.

thanks

paul