sizeMask = function () {
		var $M		= $(this)
		,	pane	= $M.data("layoutMask") // eg: "west"
		,	s		= state[pane]
		;
		// only masks over an IFRAME-pane need manual resizing
		if (s.tagName == "IFRAME" && s.isVisible) // no need to mask closed/hidden panes
			$M.css({
				top:	s.offsetTop
			,	left:	s.offsetLeft
			,	width:	s.outerWidth
			,	height:	s.outerHeight
			});
		/* ALT Method...
		var $P = $Ps[pane];
		$M.css( $P.position() ).css({ width: $P[0].offsetWidth, height: $P[0].offsetHeight });
		*/
	}
sizeMask

	Needed to overlay a DIV over an IFRAME-pane because mask CANNOT be *inside* the pane
	Called when mask created, and during livePaneResizing