Create reliable integration tests for verifying GUI plugins

[azeey]

Desired behavior

We have a small set of unit tests for the GUI, but lack testing that requires emulating user input. #2085 was an attempt to add one, but it is not reliable.

Alternatives considered

None

Implementation suggestion

Build on top of #2085

Additional context

[XINJIANGMO]

In my spare time , I will work on this and other GUI plugins.