code: protected void positionHelper() {
  
          if (m_dragHelper == null) {
              // should never happen
              CmsDebugLog.getInstance().printLine("Drag helper is null");
              return;
          }
          Element parentElement = m_dragHelper.getParentElement();
          int left = CmsDomUtil.getRelativeX(m_clientX, parentElement) - m_cursorOffsetX;
          int top = CmsDomUtil.getRelativeY(m_clientY, parentElement) - m_cursorOffsetY;
          m_dragHelper.getStyle().setLeft(left, Unit.PX);
          m_dragHelper.getStyle().setTop(top, Unit.PX);
      }
docs: Positions an element depending on the current events client position and the cursor offset. This method assumes that the element parent is positioned relative.<p>