var isDOM = (window.addEventListener);

document.oncontextmenu = function(e)
{
	if ( isDOM && ( e.target.form == undefined || ( e.target.tagName == "INPUT" && e.target.type == "image" ) ) )
	{
		e.stopPropagation();
		e.preventDefault();
		return( false );
	} else if ( !isDOM && ( event.srcElement.form == undefined || ( event.srcElement.tagName == "INPUT" && event.srcElement.type == "image" ) ) ) {
		event.cancelBubble = true;
		event.returnValue = false;
		return( false );
	}
}