The basic structure is nice start, but currently it is limited to binary branching. Would it be possible to add either this:

This would make it significantly easier to work with certain constructions.
But even better would be:

This would allow easy creation of the above structure with three branches and also easily extending the binary one:

Also, it would be helpful to simply have the Category label readily at hand for attaching to the top of a given structure.

And I'm going to assume that at some point in future beta releases, short cuts will be available for bold and italics, as well as for copying and pasting.
Thanks, I'm excited about the potential for all of this.