code: public void addButtonLeft(Component button) {
  
          if (m_buttonsFolded && !isAlwaysShow(button)) {
              m_leftButtons.addComponent(button);
          } else {
              m_itemsLeft.addComponent(button);
          }
          updateFoldingThreshhold();
      }
docs: Adds a button to left toolbar side.<p>
  
  @param button the button