function HintImage(hint, defaultImage)
{
	// define functions
	this.add = add;
	
	// define constants
	var HINT = document.getElementById(hint);
	var DEFAULT;
	
	if(defaultImage == null)
	{
		DEFAULT = HINT.src;
	}
	else
	{
		DEFAULT = defaultImage;
	};
	
	/**
	 * Function: add
	 *	Add mouseover events to any element with an id.
	 *
	 * @param overElement - the dom element to apply the mouse events to.
	 * @param src - the image file to change the hint to.
	 */
	function add(overElement, src)
	{
		var over = document.getElementById(overElement);
		
		over.onmouseover = function()
		{
			HINT.src = src;
		};
		over.onmouseout = function()
		{
			HINT.src = DEFAULT;
		};
	};
};