function setTall() {
	if (document.getElementById) { // Do you know the DOM?
		var divs = new Array(document.getElementById('left_frame_div_id'), document.getElementById('right_frame_div_id'), document.getElementById('main_frame_div_id'));
		var maxHeight = 0;

		for (var i = 0; i < divs.length; i++) { // Get the height of the tallest column
			if(i == 1) {
				if (divs[i].offsetHeight > maxHeight) maxHeight = divs[i].offsetHeight;
			} else {
				if (divs[i].offsetHeight > maxHeight) maxHeight = divs[i].offsetHeight;
			}

		}

		for (var i = 0; i < divs.length; i++) { // set the height of all columns
			divs[i].style.height = maxHeight +'px';
		}
		divs[0].parentNode.style.height = maxHeight + 'px';
	}
}

window.onload = function() {
	setTall();
}

window.onresize = function() {
	setTall();
}