Cancel events from other events (#2433)
* WIP
* Use async iteration
* Format + comment
* Very hacky WIP
* Fix synchronization
* Add comments + tidy up implementation
* Remove print
* Fix rebase
* Lint
* Disconnect queue when cancelled
* Add stop button for interface automaticallY
* Unit tests + interface fixes
* Skip some tests on 3.7
* Skip in 3.7
* Fix skip message
* Fix for python 3.7
* Add stop variant to button variant type union
* CHANGELOG
* Add demos/gifs to the changelog
