When trying the OpenGL 4 driver, tabbing out of the game works fine, however switching back to the client does not push the client's window to the top. All inputs are being received by the client though.

If I completely hide the client with Command-h and tab back to it, its window does get pushed correctly to the top and everything works fine.

Edit: That's on OS X 10.9.5

This also happens on OS X 10.10.

Thanks for the report.

No matter what I try, I can't get it to put the window on top when alt-tabbing back to VO. If I alt-tab to it again (with VO still the active app) then it puts the window on top.
Sorry, I'm unable to fix it at this time.