Summary

During the sprint, we were looking at widgets, and I noticed that theMultiCursor constructor takes aFigureCanvasBase as first parameter. This probably exists to say where to connect signals, but this does not match how any of the other widgets work, which infer this from the suppliedAxes. Theoretically, I don't see any reason why theAxes need to be on a singleFigure forMultiCursor to work, but that's implied by it only using a single canvas.

Proposed fix

The canvas should be found from theAxes, and the constructor should assert that all suppliedAxes are on the sameFigure (if that is indeed required.)

However, I don't know how to deprecate this. If we use_api.delete_parameter, then the remaining parameters become keyword-only, but we don't want to do that to theAxes parameter, which should have been the first positional parameter.