Reinout van Schouwen said about Embedding Mozilla...
> Let's build a GTK+ shell around it and call it Galeon! =)
Actually, that's an interesting point. What I talked about is more like a mixture of embedding a browser (Galeon) and messing with the document content in a scripting language (Greasemonkey).
So, nothing new under the sun, but one more way of doing the same that may be more convenient in some occasions.
In Sugar, the single reason why we cooked our own solution is so the user can study the code of our browser and make modifications to it as easily as possible (freedom 3). We don't want the user to just 'use' the software we provide and to calmly wait for the next release, but we want them to 'create' new tools based on what we provide.
At the end of the day, Sugar is not one more productivity desktop, but a learning platform. And in the same way that each individual learns in his/her own way, they need to be able to suit their learning tools to their learning habits.
Perhaps not everybody that uses Sugar will learn to code, but at least those people that have the inclination to write small amounts of code (spreadsheet macros, for example) will be able to add a button there, transform the document viewed, etc. And then share it with their friends.