function winh(prm){	
	var h =  document.body.clientHeight;
	var divh = document.getElementById(prm);
	divh.style.marginTop = ((h-divh.clientHeight)/2) +"px";
}

function md(e) 
{ 
try { if (event.button==2||event.button==3) return false; } 
catch (e) { if (e.which == 3) return false; } 
}
document.oncontextmenu = function() { return false; }
document.ondragstart = function() { return false; }
document.onmousedown = md;