Yes, the scroll wheel forward expands to the full size, and backwards reduces it to one line; this is as designed, and only on the wheel for lack of a better UI idea.
I can't say that it has any amount of documentation or discoverability :-(

I see what you mean about the "jitter" on expand contract.  I can't think of a way to handle, but if I ever open the source again I'll think about some sort of hysteresis.

Paul

On Tue Oct 28 2014 at 3:55:39 PM erik quanstrom <quanstro@quanstro.net> wrote:
On Mon Oct 27 23:49:06 EDT 2014, paul.a.lalonde@gmail.com wrote:

> What do you mean by resizing flicker?  I've never seen it with the
> multi-line tags.  And we do resize the tag by hand - the scroll wheel opens
> and shuts it, in addition to adding/removing the trailing newline.

i didn't realize there was the scroll wheel trick.  it doesn't work when
the tag is empty, or allow one to expand the tag window larger than the
current tag.

what i mean by "flicker" is that if i modify a file which has
a tag line that is close to wrapping, then modifying the file
will often make the tag line too long, and wrapping.  Undo
has the opposite effect.

- erik