John Gruber posts a follow-up about clickthrough. He puts the ball into Apple’s court:

Only Apple can fix this. Where by “fixing it”, I mean three things, all essential:

    Mandate correct click-through behavior in the HIG.
    Make Apple’s Cocoa frameworks do the right thing by default. Supply sufficient API hooks so that it’s easy for third-party frameworks to do the right thing.
    All of Apple’s own software needs to follow these guidelines.

Hmm… I need an “applause” smiley here…

Here’s an additional interesting tip from Sven-S. Porst:

One thing I’d like to add on the topic of click-through is that while it had been possible for ages in MacOS to drag background windows without activating them by holding the command-key while doing so, support for this background manipulation has improved in OSX. In Cocoa applications you can command-click most controls and use them without activating the window first. I like that. Click-through for the people who want and it and can handle it. It’s far from perfect, though, as it doesn’t work uniformly through all applications and doesn’t work for toolbar items either as the command-Key is used for moving items there.