Include path search in Creator

It would be nice if one could search for a symbol or file in the include path. Right now you can search symbols in files that you have included already, and that's cool, but sometimes you don't know which include file a symbol is in, and thus you don't know what to include.

If my include path is set to in include /usr/include/ then the headers in this directory could be indexed, and then I could use the search functionality in Qt Creator to find where a class is defined.