// JavaScript Document

// vertical slider control
var slider = new Control.Slider('handle', 'track', {
	axis: 'vertical',
	onSlide: function(v) { scrollVertical(v, $('text'), slider);  },
	onChange: function(v) { scrollVertical(v, $('text'), slider); }
});


// scroll the element vertically based on its width and the slider maximum value
function scrollVertical(value, element, slider) {
	element.scrollTop = Math.round(value/slider.maximum*(element.scrollHeight-element.offsetHeight));
}

// disable vertical scrolling if text doesn't overflow the div
if ($('text').scrollHeight <= $('text').offsetHeight) {
	slider.setDisabled();
	$('track').hide();
	$('sliderUp').hide();
	$('sliderDown').hide();	
}