/* Centring Effect. Extends scriptaculous Effect Object */

Effect.Centre = function(element) {

	/* 	# %PUBLIC%
		# NAME:*		Effect.Centre
		# DESCR:*		Centre the passed element on the screen.
		# USAGE:*		new Effect.Centre('infoBox');
		# RETURNS:*		Nothing. 
		# %ENDPUBLIC% */

	try {
		element = $(element);
	} catch(e) {
		return;
	}

	element.style.position = 'absolute';

	var arrayPageSize = obtainPageSize();

	var scrollY = obtainDocumentScrollTop();

	var elementDimensions = Element.getDimensions(element);
	var setX = (arrayPageSize[2]  - elementDimensions.width) / 2;
	var setY = (arrayPageSize[3] - elementDimensions.height) / 2 + scrollY;

	setX = ( setX < 0 ) ? 0 : setX;
	setY = ( setY < 0 ) ? 0 : setY;

	element.style.left = setX + "px";
	element.style.top  = setY + "px";

}