Focus-follows-mouse mode. Possible? How?

Hi everyone,

Is it possible to configure one's Mac windowing system to use focus-follows-mouse, like the way the X Window System works?

I got used to using the mouse in a focus-follows-mouse mode, and it is very confusing using the current system: I don't know if when I click the pointer in a window, whether that click will,

1) only raise and focus the window (those are tied together for whatever reason on current windowing systems), or

2) also send the click event into the window to be processed by the application.

So, I've resorted to clicking in a window in an "inactive" area, i.e. not a button or action area, in order to achieve 1, but not 2.

I'd rather just have focus-follows-mouse, so that I can skip the "click", and know that the window is focused, but not raised (which is good when I just want to read from one and type into another).

So, is this possible on Mac?