The green button tries to remove all scroll bars and it will also shrink the window down to where there are just no scroll bars (i.e. shrinking it one more pixel would activate the scrollbars).

It fits the window to the size of the content. Or something. Can't deny it's confusing and I never use it myself

I'll have to give cinch a try, I've just gotten used to really janky window layouts in OS X.

sizes the window to best fit the content (in theory). I think it's up to the application to specify that size though.

Works very well in Safari, but always seems to go to full screen for Firefox. Chrome's working sort of as expected here alternating between best fit and some stupid tiny size it seems to have concocted.

In old MacOS it was called "zoom", not "maximize" and the application developer was supposed to swap between the "ideal small size window" and the "ideal large size window".

In this age of cross-platform apps, and people who are used to "maximize" instead of "zoom" it is a concept that has been long forgotten

Coming from Windows this confused me as well. I found an article that clarifies why it behaves the way it does; it does make sense to do it this way particularly on high res screens where the empty space would be glaring.

http://www.macyourself.com/2011/02/06/why-doesnt-mac-os-xs-g...