What version(s) of WoW are you using?

Classic Era

What problem are you experiencing that led to you asking for this feature?

Using the Extended Seach Options window while browsing for unknown recipes at the AH, u cant filter out the known ones without having to hover over each and read if its already known.

other case, ur browsing for weapon upgrades while lvling an alt, u have to scan for each known weapontype seperately.

What solution would you like?

A "Usable Items" checkbox in the Extended Seach Options window that functions like the ingame one would be lovely. (the one ontop of "Display on Character" in the default browse tab)
And it would help in more than the named scenarios i guess.

Any alternatives you can think of?

No response

Anything else?

No response