[ENHANCEMENT] Add communication between tabs

[MBartkowiakSTFC]

Is your feature request related to a problem? Please describe.
The users are inclined to click the "run" button several times, starting multiple copies of the same job.

Describe the solution you'd like
The converter and action tabs should contain an embedded display showing how many jobs are running at the moment. There should be an indication that a new job has been started every time "run" is pressed.

Describe alternatives you've considered
The Run button should change appearance when it is activated, and become disabled for a few seconds. This would help address #593

Additional context
N/A