Center ButtonField in a FieldManager

Question

I wanna center a buttonField in a HorizontalFieldManager
i tried that code :

   HorizontalFieldManager ButM = new HorizontalFieldManager(Field.FIELD_HCENTER|USE_ALL_WIDTH)
    {
        public void paint(Graphics graphics)
        {
            graphics.setBackgroundColor(0x00000000);
            graphics.clear();
            super.paint(graphics);
        }  
    };
    ButtonField Order = new ButtonField("Tri",Field.FIELD_HCENTER|ButtonField.CONSUME_CLICK);

But the ButtonField is not centred, am i doing something wrong ?

EDIT :
I solved this problem by using this code :

HorizontalFieldManager ButM = new HorizontalFieldManager(HorizontalFieldManager.FIELD_HCENTER|USE_ALL_WIDTH)
    {
      public void paint(Graphics graphics)
      {
          graphics.setBackgroundColor(0x00000000);
          graphics.clear();
          super.paint(graphics);
      }  
    };
    ButtonField Order = new ButtonField("Tri",DrawStyle.HCENTER|ButtonField.CONSUME_CLICK);
    Order.setMargin(0,0,0,(Display.getWidth()/2)-30);

Answer 1

HorizontalFieldManager ButM = new HorizontalFieldManager(HorizontalFieldManager.FIELD_HCENTER)
{
  public void paint(Graphics graphics)
  {
      graphics.setBackgroundColor(0x00000000);
      graphics.clear();
      super.paint(graphics);
  }  
};
ButtonField Order = new ButtonField("Tri",DrawStyle.HCENTER|ButtonField.CONSUME_CLICK);
Order.setMargin(0,0,0,(Display.getWidth() - Order.getPreferredWidth())/2 );
ButM.add(Order);

This code will run fine.. I have test it...