There are many places in Fogbugz where you can/have to type case numbers. For example when resolving a case as duplicate, or linking cases to each other by typing 'case NNN' in a comment.
Right now, I have to look up the case number, copy or remember it, then paste or type it again in some other place.
Basically I'm suggesting that all places where you can enter case numbers should offer a drop down box that lists all recent case numbers with their titles (like the 'star' menu). Currently, if you type a case number, a dropdown menu appears that shows matching cases, but that still requires you to start with the correct digits so it doesn't really solve anything.
And in the comments editor, if I type 'case ', a drop down menu with recent cases should appear immediately, with keyboard control.