var smenu=null;

  function chgbkovr(src) {
     src.style.backgroundImage="url(images/btngl.gif)";
  }

  function chgbkout(src,sub) {
     if (src.id == smenu)  {
       src.style.backgroundImage="url(images/btnr.gif)";
       return;
     }

     if (sub) {
       src.style.backgroundImage="url(images/btny.gif)";
     } else {
       src.style.backgroundImage="url(images/btng.gif)";
     }
  }
  /*
  function chgbkclk(src,sub) {
     src.style.backgroundImage="url(images/btnr.gif)";
     if (sub) {
       ssmenu=src;
     } else {
       smenu=src;
       ssmenu=null;
     }
     if (ssmenu==null) hidealldoc('link');
  } */


  var docs=new Array('about','user','link');

  function switchdoc(id){
      hidealldocs(id);
      showdoc(id);
  }

  function hidealldocs(id){
      for (var i=0;i<docs.length;i++){
          if (docs[i] != id) {
            hidedoc(docs[i]);
          }
        }
  }
  function hidedoc(id) {
        //var tid = 't'+id
        if (document.getElementById) {
          document.getElementById(id).style.display = 'none';
          //document.getElementById(tid).style.backgroundImage="url(images/btng.gif)";
        } else {
          if (document.layers) {
            document.id.display = 'none';
          } else {
            document.all.id.style.display = 'none';
          }
        }
  }

  function showdoc(id) {
        if (document.getElementById) {
            if (document.getElementById(id).style.display != 'block') {
                document.getElementById(id).style.display = 'block';
                document.getElementById(id).style.visibility = 'visible';
            } else {
                document.getElementById(id).style.display = 'none';
                document.getElementById(id).style.visibility = 'hidden';
            }
        } else {
            if (document.layers) {
              if (document.id.display != 'block') {
                  document.id.display = 'block';
                  document.id.visibility = 'visible';
              } else {
                  document.id.display = 'none'
                  document.id.visibility = 'hidden';
              }
              //document.tid.backgroundImage="url(images/navbarr.gif)";
            } else {
              if (document.all.id.style.display != 'block') {
                  document.all.id.style.display = 'block';
              }
              //document.all.tid.style.backgroundImage="url(images/navbarr.gif)";
            }
          }
   }