John Gruber affirms a conviction I’ve long held, namely that “clickthrough” is usually a bad idea in Mac OS X applications. In the process, he goes into interesting detail about the Mac’s emphasis on the frontmost window, and how this differs from Microsoft’s window-centric approach.

The concept of the frontmost (or active) application is absolutely essential to understanding how to use a Mac. The frontmost application controls the menu bar and handles all keyboard input, including command key shortcuts. The concept of the frontmost window is related and similarly important. You can click on background windows (thus giving rise to the potential for click-through), but that’s it – everything else you can do with your computer is directed at the frontmost window of the active application…