var Drag = {
  
          obj : null,
  
          init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
          {
                  o.onmousedown        = Drag.start;
  
                  o.hmode                        = bSwapHorzRef ? false : true ;
                  o.vmode                        = bSwapVertRef ? false : true ;
  
                  o.root = oRoot && oRoot != null ? oRoot : o ;
  
                  if (o.hmode  && isNaN(parseInt(o.root.style.left  ))) o.root.style.left   = "0px";
                  if (o.vmode  && isNaN(parseInt(o.root.style.top   ))) o.root.style.top    = "0px";
                  if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right  = "0px";
                  if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";
  
                  o.minX        = typeof minX != 'undefined' ? minX : null;
                  o.minY        = typeof minY != 'undefined' ? minY : null;
                  o.maxX        = typeof maxX != 'undefined' ? maxX : null;
                  o.maxY        = typeof maxY != 'undefined' ? maxY : null;
  
                  o.xMapper = fXMapper ? fXMapper : null;
                  o.yMapper = fYMapper ? fYMapper : null;
  
                  o.root.onDragStart        = new Function();
                  o.root.onDragEnd        = new Function();
                  o.root.onDrag                = new Function();
          },
  
          start : function(e)
          {
                  var o = Drag.obj = this;
                  e = Drag.fixE(e);
                  var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
                  var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
                  o.root.onDragStart(x, y);
  
                  o.lastMouseX        = e.clientX;
                  o.lastMouseY        = e.clientY;
  
                  if (o.hmode) {
                          if (o.minX != null)        o.minMouseX        = e.clientX - x + o.minX;
                          if (o.maxX != null)        o.maxMouseX        = o.minMouseX + o.maxX - o.minX;
                  } else {
                          if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
                          if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
                  }
  
                  if (o.vmode) {
                          if (o.minY != null)        o.minMouseY        = e.clientY - y + o.minY;
                          if (o.maxY != null)        o.maxMouseY        = o.minMouseY + o.maxY - o.minY;
                  } else {
                          if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
                          if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
                  }
  
                  document.onmousemove        = Drag.drag;
                  document.onmouseup                = Drag.end;
  
                  return false;
          },
  
          drag : function(e)
          {
                  e = Drag.fixE(e);
                  var o = Drag.obj;
  
                  var ey        = e.clientY;
                  var ex        = e.clientX;
                  var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
                  var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
                  var nx, ny;
  
                  if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
                  if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
                  if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
                  if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);
  
                  nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
                  ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));
  
                  if (o.xMapper)                nx = o.xMapper(y)
                  else if (o.yMapper)        ny = o.yMapper(x)
  
                  Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
                  Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
                  Drag.obj.lastMouseX        = ex;
                  Drag.obj.lastMouseY        = ey;
  
                  Drag.obj.root.onDrag(nx, ny);
                  return false;
          },
  
          end : function()
          {
                  document.onmousemove = null;
                  document.onmouseup   = null;
                  Drag.obj.root.onDragEnd(        parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]), 
                                                                          parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));
                  Drag.obj = null;
          },
  
          fixE : function(e)
          {
                  if (typeof e == 'undefined') e = window.event;
                  if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
                  if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
                  return e;
          }
  };