The search for the "Go To" items look like they were taken from IDEA, which was optimized for Java and camel-casing. It does not work terribly well for Ruby. I have to spend too much time thinking about whether something is a class or a module or a daemon or something else. On top of that, partial searches don't work very well and everything is case-sensitive.
I'd highly suggest modeling this off TextMate's Cmd-T search. It is far more forgiving and far more usable. Additionally, a lot of potential RubyMine users will have used TextMate and will expect something similar.
Issue was resolved
I would not use * as a wildcard but a space instead (like in textmate) which allows very natural typing and faster searching.
Moreover I would not only search at the beginning of the filenames. Specially for partials this is quite cumbersome since I always search for the filename but I forget to prepend it with the underscore.
For example typing "me co spe" to find the messages_controller_spec.rb is much easier than me*co*spe*.
For now, we've implemented Christian's suggestions. Space can now be used as word separator (for example, "na te" now matches "name_util_test"), and leading underscores in filenames are ignored ("form" now matches "_form.html.erb").
Additional specific examples on what you expect to be matched are welcome.
Take a class named "UsersControllerTest" in a file named "users_controller_test"
Typing "uct" will not work. Not in the class name search and not in the filename search. "UCT" will work for both searches, even though the filename is lowercase. "u c t" will also work in both. "u c t " will not work in either.
These are all variations of the same three letters. Yet, the simplest of the forms to type is not supported at all.
I can appreciate you find the TextMate approach too lenient, but I would really consider the target market here. I've been using IDEA for years as my Java IDE. I've been using TextMate and RubyMine for some time for Ruby development. My personal opinion is that TextMate really has this one right. I would rather have a false negative than a false positive. At least with the false negative I can ignore it in the list. With a false positive I have to start clicking through the project explorer.
If this one issue were resolved satisfactorily, I probably could sell my whole team on RubyMine. As it stands, most won't even bother to use it because navigating to files is too much effort.