gistfile1.js

function slideRight(elm, seconds, opts) {
	elm = glow.dom.get(elm);
	opts = opts || {};
	// make the tween easeBoth by default
	opts.tween = opts.tween || glow.tweens.easeBoth();
	
	// get the full width of the item
	var currentWidth = elm[0].style.width,
		fullWidth,
		anim;
	
	elm[0].style.width = '';
	fullWidth = elm.css('width');
	elm[0].style.width = currentWidth;
	
	anim = glow.anim.css(elm, seconds, {
		width: fullWidth
	}, opts);
	
	// unset the width when the anim completes, needed for relative widths (so they resize)
	glow.events.addListener(anim, 'complete', function() {
		elm[0].style.width = '';
	});
	
	// make the animation
	return anim.start();
}

function slideLeft(elm, seconds, opts) {
	elm = glow.dom.get(elm);
	opts = opts || {};
	// make the tween easeBoth by default
	opts.tween = opts.tween || glow.tweens.easeBoth();

	// make the animation
	return glow.anim.css(elm, seconds, {
		width: 0
	}, opts).start();
}

// usage:

// You can use CSS selectors or NodeLists to animate
slideLeft('#elementToAnimate', 3);
slideRight('#elementToAnimate', 3);

// You can give it the same options as http://www.bbc.co.uk/glow/docs/1.7/api/glow.anim.shtml#staticmethod:css
slideLeft('#elementToAnimate', 1, {
	onComplete: function() {
		alert("I've completed!");
	}
});