ns = (document.layers)? true:false 
ie = (document.all)? true:false 

if (ns) document.captureEvents(Event.MOUSEMOVE | Event.MOUSEDOWN) 

document.onmousedown = mouseDown; 
document.oncontextmenu = mouseDown; 

function mouseDown(ev)
{
if (ie)
{ if (event.button != 1) { return false; } }

if (ns) { if (ev.which == 3) { return false; } }

}