MouseScroll.scala

def addMouseScroll[A](comboBox: JComboBox[A]): Unit = {
    comboBox.addMouseWheelListener(new MouseAdapter {
      override def mouseWheelMoved(e: MouseWheelEvent): Unit = {
        val itemCount = comboBox.getItemCount
        val index = comboBox.getSelectedIndex + e.getWheelRotation
        val newIndex = if (index < 0 ) itemCount + index else index % itemCount

        comboBox.setSelectedIndex(newIndex)
      }
    })
  }