Yes, it's a flaw in an extension, not the compiled program, but it highlights one of my biggest complaints about FF. Out of the box it basically has no features, to speak of, by modern browser standards. That means you have to hunt down and load a bunch of extensions, if you're a feature junky (like me).

But the rub is, these extensions are written by everybody and their brother. Not only is there no real quality control over them, but the people writing them don't know each other, and they don't test for compatibility issues.