code: private void installDragOverlay() {
  
          if (m_dragOverlay != null) {
              m_dragOverlay.removeFromParent();
          }
          m_dragOverlay = DOM.createDiv();
          m_dragOverlay.addClassName(I_CmsLayoutBundle.INSTANCE.dragdropCss().dragOverlay());
          Document.get().getBody().appendChild(m_dragOverlay);
      }
docs: Installs the drag overlay to avoid any mouse over issues or similar.<p>