if (document.images) {
    homebuttonup       = new Image();
    homebuttonup.src   = "../images/toprnav-home1off.gif" ;
    homebuttondown     = new Image() ;
    homebuttondown.src = "../images/toprnav-home1on.gif" ;
    
    mapbuttonup       = new Image();
    mapbuttonup.src   = "../images/toprnav-sitemapoff.gif" ;
    mapbuttondown     = new Image() ;
    mapbuttondown.src = "../images/toprnav-sitemapon.gif" ;
    
    artbuttonup       = new Image();
    artbuttonup.src   = "../images/topnav-articlesoff.gif" ;
    artbuttondown     = new Image() ;
    artbuttondown.src = "../images/topnav-articleson.gif" ;
            
    addbuttonup       = new Image();
    addbuttonup.src   = "../images/topnav-addsiteoff.gif" ;
    addbuttondown     = new Image() ;
    addbuttondown.src = "../images/topnav-addsiteon.gif" ;
            
    logbuttonup       = new Image();
    logbuttonup.src   = "../images/topnav-loginoff.gif" ;
    logbuttondown     = new Image() ;
    logbuttondown.src = "../images/topnav-loginon.gif" ; 
            
    freeadbuttonup       = new Image();
    freeadbuttonup.src   = "../images/topnav-freeadsoff.gif" ;
    freeadbuttondown     = new Image() ;
    freeadbuttondown.src = "../images/topnav-freeadson.gif" ;
}
function buttondown( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "up.src" );
    }
}