Allow blocking execution of plot_alignment() and stc.plot()

The alignment and the Brain plots are both used in interactive exploration and in non-interactive scripts.

A common annoying issue that I and other users regularly run into is that we write a short script that displays the sensor alignment or a SourceEstimate, run it (e.g. via the Run button in VS Code), the window pops up – and immediately disappears. So one then needs to run the script again – this time, with python -i or after inserting some blocking call like input().

It would be great if there was an easier way to ensure a blocking behavior.

cc @GuillaumeFavelier

[hoechenberger]

Ah ok! Thought we’d always had this param. In that case – let’s block it 😁👌

[GuillaumeFavelier]

I do not mind changing the name if it does the same thing.