code: public void enable() {
  
          updateState("up");
          m_enabled = true;
          // show the current file input field
          if (m_fileInput != null) {
              m_fileInput.getElement().getStyle().clearDisplay();
          }
          super.setTitle(m_title);
      }
docs: Enables the button, switching the button title attribute from the disabled reason to the original title.<p>