> for a lot of people who are already employed, permission must be obtained from current employer before contributing to open source

I am always puzzled about contract clauses that try to limit what an employee can do in their free time. I understand that some people may be in a bad situation and have no choice but to put up with it. But if we're really in a seller's market, as everyone says, how can this kind of thing become a tendency?

It's actually usually not the employer, but the local dept of labor laws - for salaries employees, unless explicitly stated otherwise - your employer generally "owns" anything you do in your line of work, even on your own time. So for example if you work for a game studio, coming up with an idea for a game would auto-magically make it your employer's property, even if you did it on a sunday morning.

This is further reinforced by various employer-specific clauses in the hiring contract / code of conduct.

Its screwed up but its the world we live in.

I don't sign contracts like these. Actually, I refuse even to work for employers who put it in and then take it out when asked because the trust has already gone if you demanded to own the work I do on a Sunday afternoon.

Any employer who puts that clause in their contract and whinges about not being able to find good developers has only themselves to blame.