Thank you both, this is exactly what I was looking for!
But I ran into an issue (maybe this is Windows (10) specific):
once I open the window, the original Pharo window is no longer responsive. It is not frozen, I can see a cursor blinking in the playground, but clicking anywhere or pressing any key doesn't do anything.
This behavior persists even after I close the new window.
Only when I press ctrl (without anything else) the content of the playground gets executed again, but that's it.
Who knows whether OSWindow is maintained? Who knows if anybody cares that it
doesn't work on Windows?
OSWindow is like lots of things that suddenly appear in the Pharo standard
image. There's no documentation. There's no plan. That's the Pharo way. Give
it a year or two and it will be superseded by another framework doing the
same thing which will also have no documentation, killer bugs, and no plan.