Ah, I see, this seems to require a custom solution. Well. such wildcards would be nice, but also some kind of luxury item, which in economic times like these might not be affordable.
i hacked this into my copy a couple months ago because i was losing money with all the time wasted switching between patch & data dirs -- a symbol reciever to openpanel in x_gui.c and send that to the openpanel in u_main.tk with: -initialdir dir -file_types {{"wave files"{.wav}}} etc...
you can have multiple like {.wav .aiff .sdII} for a single type, so perhaps a new inlet accepting a list would be more your style....