Some quick observations on new site builder
Using Jamroom
I think the best solution to this is some type of "preview" mode when editing a widget - we might be able to work in a "source" type component at that time, but it would be hard as most widgets are NOT templates but direct PHP code.
However I have to agree with Michael on this that extra buttons/functions for the most part are only going to confuse users who do not understand "why" they are there (trust me - ANYTHING added beyond what is absolutely necessary is going to confuse some users) - and when they click on it they will not understand it and will come here posting questions about it.
SB is designed to be the "easy to use" side of Jamroom. For those that want to see the "code" side of things you can always dig into the templates.