ViewSourceWith has the ability to edit/show css and js in an external application, see its settings/view. And it can do (just about) anything the Open with ... extension could, I think. (For example, you can a send link target to any application you wish, it isn't limited to editors.) Are you missing something in particular?
But to have a PSPad-specific Firefox extension isn't a bad idea. I will think about this ... B-] -- <http://forum.pspad.com/read.php?2,33688,33690> PSPad freeware editor http://www.pspad.com
