One shared menu bar at the top of the screen is supported by Fitts's Law, which says that targets at the edge of the screen are faster and easier to click:
http://en.wikipedia.org/wiki/Fittss_law
No comment on the rest.
Fitt's Law also says that closer targets are easier to click, and is concerned only with how long it takes to move the mouse pointer rather than how that fits into the larger picture of what you're doing.
Having the menu separate from the window breaks spatial locality and associates the menu to the computer rather than to the application.
And this is mostly relevant on big screens like the biggest iMacs. It's just wrong, imo.
Re:Lying Microsoft Advertising
by snogglethorpe on Thursday May 23, 2013 @10:56PM
(#5761023)
Gnome doesn't require "click-to-raise," though it's the default.
I prefer systems with a window manager that actually supports multi-tasking.
Having one shared menu bar is a pain. Having a row of icons for possibly-already-running applications, instead of a list of what windows you have open, is a pain.
Click-to-raise is less of a pain, but still annoying. Which is why I run XFCE on my desktop at home, since MS Windows and Gnome (and I think KDE?) get this one just as wrong as Apple does.