Define/Run *master* document

This is more a request than a issue. I find myself a lot of times editing a lot of scripts (say, python scripts) that belong to the same project where one file contains the `__main__` method. To be able to run the script I need to cursor (focus) the main document with the `__main__` method and run it.

It would be nice to add a couple of short-cuts for focusing a script and selecting it as a _master_ document, and later from any script press another short-cut to rune that _saved master_ document.

Something like:

Ctrl+Alt+M: set current document as _master_ document
Ctrl+Shift+M: run previously saved _master_ document

Thank you!