function onm(obj)
{
    var   divs   =   document.getElementsByTagName("DIV");     
    for(var   i   =   0;i<divs.length;i++)  
      {      
          if(divs[i].id.indexOf("gl_") !=-1)
          {
             document.getElementById(divs[i].id).style.backgroundImage="url(images/white_28.jpg)";
          }        
      } 
      obj.style.backgroundImage="url(images/zibg_28.jpg)";
}