Mysteriously dimmed menu items

AskTog's Bughouse is a list of beefs with recurring bad design in software. Bug #4 is Mysteriously dimmed menu items:

"Designers offer no way for users to discover why a given menu or option has been dimmed (grayed out), nor how to turn it back on."

The proposed fix:

"Make grayed-out objects clickable, revealing what has caused the object to be dimmed and what the user can do about it."

I think Paint Shop Pro deserves honorable mention for an even better solution. Not only does PSP tell the user what needs to be done to make a command possible, with the user's consent, it performs the necessary fix ups and then executes the intended the would-be unavailable command.