var s_id_button='p_scrollbar_button';
var s_id_list  ='p_list';

var s_move_allowed=false;
var s_max_top=400;
var s_m_top=0;
var s_off=0;
var s_mov=0;

function s_mouse_down(m_event)
{
  s_move_allowed=true;
  
  if(!m_event)
    m_event=window.event;
  
  s_off=m_event.clientY-s_mov-150;
}

function s_mouse_up(m_event)
{
  s_move_allowed=false;
}

function s_move(m_event)
{
  if(s_move_allowed)
  {
    if(!m_event)
      m_event=window.event;
  
    mov=m_event.clientY-150-s_off;
    
    mov=mov<0?0:(mov>s_max_top?s_max_top:mov);
    s_mov=mov;
  
    s_top=-Math.floor(mov/s_max_top*s_m_top);
    
    document.getElementById(s_id_button).style.top=""+mov+"px";
    document.getElementById(s_id_list).style.top=""+s_top+"px";
  }
}

function s_init()
{
  document.onmousemove=s_move;
  document.getElementById(s_id_button).onmousedown=s_mouse_down;
}