It occurred to me a few weeks ago that I may have done myself a dirty by installing a gift copy of Photoshop (and Bridge) CS4. It's just possible that any Adobe or third-party .8BF-extension plug-ins I might get from here on out will only work in Photoshop itself and not in IrfanView. Which is the root and reason for my question.

Co-developers and Irfan sich-selbe please take note.