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   = (document.body.offsetWidth / 2) - (document.getElementById("root").clientWidth / 2) +'px'; 
          if (o.vmode  && isNaN(parseInt(o.root.style.top   ))) o.root.style.top    = "220px"; 
          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; 
     } 
};