function showLayer(tabgroup, tab) {   
        hideHeaders(tabgroup);    
        hideContents(tabgroup);  
        showHeader("tabHead_" + tabgroup + "_" + tab);       
        showContent("tabContent_" + tabgroup + "_" + tab);
    }
     
    function hideContents(tabgroup) {
        var obj = document.getElementById(tabgroup);
        var tabs = obj.getElementsByTagName("div");

        for(var i=0; i<tabs.length; i++) {
            tabs[i].style.display = "none";                                                    
        }
    }
    
    function hideHeaders(tabgroup) {
        var obj = document.getElementById(tabgroup);
        var headers = obj.getElementsByTagName("li");
        
        for (i=0; i<headers.length; i++) {
            headers[i].className = headers[i].className.replace("active", "");
        }                        
    }
    function showHeader(header) {
        document.getElementById(header).className += "active";
    }    
    
    function showContent(tab) {
        document.getElementById(tab).style.display = "block";
    }