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jquery.fn.extend({
	mousewheel: function(up, down, preventdefault) {
		return this.hover(
			function() {
				jquery.event.mousewheel.givefocus(this, up, down, preventdefault);
			},
			function() {
				jquery.event.mousewheel.removefocus(this);
			}
		);
	},
	mousewheeldown: function(fn, preventdefault) {
		return this.mousewheel(function(){}, fn, preventdefault);
	},
	mousewheelup: function(fn, preventdefault) {
		return this.mousewheel(fn, function(){}, preventdefault);
	},
	unmousewheel: function() {
		return this.each(function() {
			jquery(this).unmouseover().unmouseout();
			jquery.event.mousewheel.removefocus(this);
		});
	},
	unmousewheeldown: jquery.fn.unmousewheel,
	unmousewheelup: jquery.fn.unmousewheel
});
jquery.event.mousewheel = {
	givefocus: function(el, up, down, preventdefault) {
		if (el._handlemousewheel) jquery(el).unmousewheel();
		if (preventdefault == window.undefined && down && down.constructor != function) {
			preventdefault = down;
			down = null;
		}
		el._handlemousewheel = function(event) {
			if (!event) event = window.event;
			if (preventdefault)
				if (event.preventdefault) event.preventdefault();
				else event.returnvalue = false;
			var delta = 0;
			if (event.wheeldelta) {
				delta = event.wheeldelta/120;
				if (window.opera) delta = -delta;
			} else if (event.detail) {
				delta = -event.detail/3;
			}
			if (up && (delta > 0 || !down))
				up.apply(el, [event, delta]);
			else if (down && delta < 0)
				down.apply(el, [event, delta]);
		};
		if (window.addeventlistener)
			window.addeventlistener('dommousescroll', el._handlemousewheel, false);
		window.onmousewheel = document.onmousewheel = el._handlemousewheel;
	},
	removefocus: function(el) {
		if (!el._handlemousewheel) return;
		if (window.removeeventlistener)
			window.removeeventlistener('dommousescroll', el._handlemousewheel, false);
		window.onmousewheel = document.onmousewheel = null;
		el._handlemousewheel = null;
	}
};