code: public JComponent createButtonBar(Size minimumButtonSize) {
  		return createButtonBar(minimumButtonSize, GuiStandardUtils.createTopAndBottomBorder(UIConstants.TWO_SPACES));
  	}
docs: Create a button bar with buttons for all the commands in this group. Adds
  a border top and bottom of 2 spaces.
  
  @param minimumButtonSize if null, then there is no minimum size
  
  @return never null