var highlighter = {
	normalImages:				{},
	highlightedImages:	{},
	
	addHighlight:
		function(buttonName, highlightFileName) {
			this.normalImages[buttonName] = new Image();
			this.normalImages[buttonName].src = "";
			this.highlightedImages[buttonName] = new Image();
			this.highlightedImages[buttonName].src = highlightFileName;
		},
		
	highlightOff:
		function(buttonName) {
			if (this.normalImages[buttonName].src != "") {
				document.getElementById(buttonName).src = this.normalImages[buttonName].src;
			}
		},
		
	highlightOn:
		function(buttonName) {
			if (this.highlightedImages[buttonName].complete) {
				this.normalImages[buttonName].src = document.getElementById(buttonName).src;
				document.getElementById(buttonName).src = this.highlightedImages[buttonName].src;
			}
		}
};