It seems to me that the Observer design pattern as described in GoF is really the same thing as Listeners found in various toolkits. Is there a difference between the concepts, or are Listeners and Observers really the same thing.
(I'm not looking for any specific computer language implementation, I just want to understand the difference (if any) from a design point of view. Yes, I know there are several answers to similar questions on SO, but they're rooted in specific questions about specific languages -- I'm looking for a design answer, not a language answer.)