How can I disable the Option+click hiding behaviour? In Mac OS X Mountain Lion at least, if you Option+click ( Alt+click ) on another a window of another app, this will make the other application to gain focus, and the current app to be hidden as if you'd pressed Command+H.

Is there any way to disable this behaviour? Perhaps with some defaults write like command entered in a terminal?

I'd like to use Option+click for some different behaviour (moving windows by Option+clicking anywhere on them, using a third-party tool, Zoom2), and having Option+click trigger the hiding behaviour instead is very inconvenient.
One option would be to remap Option+Left Click to something else using KeyRemap4MacBook.  It might not have exactly what you want, but I think it's not hard to add new shortcuts (or ask the author to add them for you).  One option that I saw was Option+Left Click -> Middle Click.  You could then (assumedly) set middle click to do what you want in Zoom2, and retain the Option+Click shortcut.  

Of course, if you do this, it will change Option+Click everywhere, even if you aren't clicking on another window.