Let's say I have a class called FooBarHandlerManager in a file called FooBarHandlerManager.cpp. In my code I can type "fbmi" and get it suggested as a type, or I can type "fooman" and it's there too. But to open the file I type Shift+Alt+O and it'll only match exact substrings of the filename, these two typing shortcuts are lost. The same goes with Shift+Alt+S.
In the olden days when I used ReSharper, it was a bit different - it would assume camel-casing and use that to filter the search a lot more, by restricting where a name could be split. Maybe that'd help here too, if you assume CamelCase or underscore_separated naming and no hardtoreadrunonnaming?
In these dialogs you can do what you want, but it works a little differently.
Type "foo hand man" and this will list all files containing *foo* AND *hand* AND *man* You can further type "foo hand man -cpp" which will exclude all files matching *cpp* from the list.
Since you can exclude as well the filtering rules are a little different. Plus these dialogs can accept and use a space character in a way that does not work when typing in the code.