var DDSPEED = 10;
var DDTIMER = 15;

// main function to handle the mouse events //
function ddMenu(id, d) {
	var h = document.getElementById(id + '-ddheader');
	var c = document.getElementById(id + '-ddcontent');
	if (c != null) {
		clearInterval(c.timer);
		if (d == 1) {
			clearTimeout(h.timer);
			if (c.maxh && c.maxh <= c.offsetHeight) {
				return
			} else if (!c.maxh) {
				c.style.display = 'block';
				c.style.height = 'auto';
				c.maxh = c.offsetHeight;
				c.style.height = '0px';
			}
			c.timer = setInterval( function() {
				ddSlide(c, 1)
			}, DDTIMER);
		} else {
			h.timer = setTimeout( function() {
				ddCollapse(c)
			}, 50);
		}
	}
}

// collapse the menu //
function ddCollapse(c) {
	c.timer = setInterval( function() {
		ddSlide(c, -1)
	}, DDTIMER);
}

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id) {
	var h = document.getElementById(id + '-ddheader');
	var c = document.getElementById(id + '-ddcontent');
	clearTimeout(h.timer);
	clearInterval(c.timer);
	if (c.offsetHeight < c.maxh) {
		c.timer = setInterval( function() {
			ddSlide(c, 1)
		}, DDTIMER);
	}
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlide(c, d) {
	var currh = c.offsetHeight;
	var dist;
	if (d == 1) {
		dist = (Math.round((c.maxh - currh) / DDSPEED));
	} else {
		dist = (Math.round(currh / DDSPEED));
	}
	if (dist <= 1 && d == 1) {
		dist = 1;
	}
	c.style.height = currh + (dist * d) + 'px';
	c.style.opacity = currh / c.maxh;
	c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
	if ((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)) {
		clearInterval(c.timer);
	}
}