A bit under the weather, but got into building buttons to control running and queued transfers today. The html and javascript side is done, with each transfer now having a cancel button, as well as a pause/start button.

Canceling queued transfers works. Canceling running transfers will need some more work, because killing a thread doesn't kill the processes being run by that thread. So I'll have to make the assistant run separate git-annex processes for transfers, that can be individually sent signals.