It's been a long awaited feature for some, v1.12.0 finally brings it : with the canvas widget, you'll be able to create custom widgets, provided that you're comfortable with Javascript and its Canvas API.
This new feature may be a bit rough around the edges, but I decided to release it nonetheless to collect feedback and hopefully improve it.
A dedicated page has been added to the documentation:
https://openstagecontrol.ammd.net/docs/widgets/canvas/
Here's is a session file with the two examples from the docs:
canvas_widget.json (5.2 KB)