Perhaps it's not exactly what you're looking for, but you can already
> I'm not sure if Sebastian has already implemented it or not. I saw my
> friends using a software on Mac called aquaminds to produce webnotes,
> and that "expand" button is very useful when presenting across the
> internet during net-work meeting.
> Here is the one example page (including the "?1" after html):
> On this page, one can see the minus sign can be clicked and become
> plus sign ...