MouseEnter/Leave Handlers

/****************************************
These functions allow you to easily set a handler for a virtual mouseleave/enter event, using my MouseBoundaryCrossing class.
/****************************************/
 
//Note that a mouseout/over event is always fired before a mouseleave/enter event
//Also note that mouseleave/enter events do not bubble; effectively, they don't bubble in this implementation either.
//usage:  elem.onmouseout = onMouseLeave(leaveHandler, outHandler);
//usage:  elem.onmouseover = onMouseEnter(enterHandler, overHandler);
function onMouseLeave(handleLeave, handleOut)
{
	if(!handleLeave) return handleOut;
	return function(evt)
	{
		evt = evt || window.event;
		if(handleOut) handleOut.call(this, evt);
		try{
			var mbc = new MouseBoundaryCrossing(evt, this);
			if(mbc.leftLandmark) handleLeave.call(this, evt);
		}catch(e){}
	}
}
function onMouseEnter(handleEnter, handleOver)
{
	if(!handleEnter) return handleOver;
	return function(evt)
	{
		evt = evt || window.event;
		if(handleOver) handleOver.call(this, evt);
		try{
			var mbc = new MouseBoundaryCrossing(evt, this);
			if(mbc.enteredLandmark) handleEnter.call(this, evt);
		}catch(e){}
	}
}