A neat function of OS X's menu bar is that all menu bars in other displays are slightly greyed out if it's not got the in focus application displayed. There is

A neat function of OS X's menu bar is that all menu bars in other displays are slightly greyed out if it's not got the in focus application displayed. There is a 'Primary Monitor' setting - this determines the window presenting the Dock and can be changed by clicking and dragging the 'menu bar' idiom between windows in the 'Arrangement' tab in the 'Displays' preference pane