Ah, ok, wildcards, indeed I didn't see that. However, although I didn't know about the feature (thanks :slightly_smiling_face: ) it *does* work for me: if I type `*file` it shows me a list of suggestions matching that (and the wildcard acts as one). It's not a *filter* as it doesn't change what the directory listing shows, but it opens a dropdown of suggestions matching what I typed. I'm on Linux, but I *assume* it would be the same on Windows, yet I could be wrong and the Windows version doesn't support that, yet I'd be a tad surprised.
Anyway, maybe you were using the Windows native file chooser dialog? This *was* removed in 2.0, see https://github.com/geany/geany/pull/3219.