It would be nice if Glib had a funtion that changed a relative path to an
absolute one (to go along with all of the other nice path functions that it
has.) An implementation of this funtion using glibmm follows:

Glib::ustring path_to_abs_path(Glib::ustring path) {
        unsigned parents = 0;
        Glib::ustring cwd = Glib::get_current_dir();
        Glib::ustring::size_type pos;

        // find out how far up we have to go.
        while( (pos = path.find("../", 0)) !=Glib::ustring::npos ) {
                path.erase(0, 3);
                parents++;
        }
        
        // now erase that many directories from the path to the current
        // directory.
        
        while( parents ) {
                if ( (pos = cwd.rfind ('/')) != Glib::ustring::npos) {
                        // remove this directory from the path
                        cwd.erase (pos);
                }
                parents--;
        }
        
        return cwd + '/' + path;
}