card_panel.add( spinner, SPINNER_KEY );
ButtonBarBuilder builder = new ButtonBarBuilder();
builder.addGrowing( card_panel );
builder.addGlue();
builder.addButton( ok_button, cancel_button );
JPanel button_panel = builder.getPanel();
button_panel.setBorder( new EmptyBorder( 0, 12, 12, 12 ) );
content_pane.add( builder.getContainer(), BorderLayout.SOUTH );