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');
 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);
 }
}