var selectedElement = "intro";
    var boxes = new Array(
            "intro", "study_programme", "family_friendly", "student_life",
            "ict", "graduates", "location",
            "application", "affordable",
            "classic_view"
    );

    function bringToFront( curEl ) {
        if( selectedElement != curEl.id ) {
            re = /\bselected\b/;

            selEl = document.getElementById( selectedElement );
            selEl.className = selEl.className.replace( re, "" );

            curEl.className = curEl.className +  " selected";

            selectedElement = curEl.id;
        }
    }