Coming back to my Unix roots (see also my previous article in German), I looked a few weeks ago for a solution for the so-called autofocus feature on my MacBook Pro. The point is that once upon a time, it was more than normal that the window on which the mouse was pointing to was the active window independently whether it had been first selected or on top of other windows.
A further flavour is mentioned in this respect as well: the autoraise feature. Here, the window where the mouse points to is not only activated, but also brought to the front. Possibly, this behaviour is not always desired (see Stevey’s Blog Rants for his “Settling the OS X focus-follows-mouse debate”).
I couldn’t find any free programs which provide the autofocus feature for the Mac. This is especially disappointing since OS X is in principle a Unix derivate. This Link provides a summary of commercial tools which, among other, provide the autofocus or autoraise feature.
The good news is that on Windows systems, the autofocus feature can be activated via the free Tweak UI PowerToy from Microsoft.