I just upgraded my macbook pro to Yosemite and this new behavior of the green window button is driving me nuts. I only want to expand a window to maximum size (and keep the menu bar showing). The new default behavior is to totally take over the screen, which is just too much, I find it disorienting. I want to go back to the way Mavericks did it.

Try doing
Alt+Shift+maximise.Also thanks to pixelfairy for finding
[BetterTouchTool](http://www.boastr.de/)to change the zoom button maximize behavior.