Simple pure Javascript drag controller slider

Hi Developers all over the world.

I would like to have some help with a simple, pure Javascript (30 lines), JQuery free (and other library's) drag control slider.

I have been searching months and found many scripts but i don't like -Jquery cause most script need 4, 5, 6 javascript includes.. I prefer smaller and basic script.. i like to ajust them like i want and i also can lean alot from smaller scripts.

All i need is a simple slider that i can use for: rescale images, scroll page, change brightness on images (with PHP) etc.

I am new with javascript (2 months), this is how far i get now.. Sorry for the bad variable names...

    <script type="text/javascript">  
      _item = null;
      mouse_x = 0;
      drag_x = 0; 
      function move_init() {
        document.onmousemove = _move;
        document.onmouseup = _stop;
      }
      function _stop(){
         _item = null;
      }
      function _move(e){
        mouse_x = document.all ? window.event.clientX : e.pageX;
        if(_item != null){
             _item.style.left = (mouse_x - drag_x) + "px";
        }
      }
      function _move_item(drag)
      {
        _item = drag;
        drag_x = mouse_x - _item.offsetLeft;
      }
move_init();
drag.onmousedown=_move_item();   // Agh.. did'nt figure out how this works
</script>

<style type="text/css">
#drag{background:#797979;color:#fff;width:30px;height:15px;position:relative;}
#track{background:red; width:200px;}
</style>

<div id="track"><div id="drag" onmousedown="_move_item(this);" >x</div></div>

i appriciate your help.

I wrote this on 31 december 2012.. So happy new year. Please be good for each other.

Thank you.