function getOffset( el ) {
    var _x = 0;
    var _y = 0;
    while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {
        _x += el.offsetLeft - el.scrollLeft;
        _y += el.offsetTop - el.scrollTop;
        el = el.parentNode;
    }
    return { top: _y, left: _x };
}
function doHideShowTopPage( ) {

		var vHeight = 0;
		var bHeight = 0;
		var y  =0; 
        if (document.all) {
          if (document.documentElement) {
            vHeight = document.documentElement.clientHeight;
          } else {
            vHeight = document.body.clientHeight
          }
        } else {
          vHeight = window.innerHeight;
        }
		//bHeight  = document.body.offsetHeight;
        //if (document.body.offsetHeight > vHeight) {
          //alert("scroolbar="+document.body.offsetHeight+" vHeight="+vHeight );
       // }else{
          //alert("sno croolbar");
        //}
		y= getOffset( document.getElementById('topOfPage') ).top;
			
		//alert(y);
		//alert(vHeight);
		if(y>vHeight+50){
		
			var el=document.getElementById('topOfPage');
			el.style.display='';
		}else{
			var el=document.getElementById('topOfPage');
			el.style.display='none';
		}

}