code: public void setSampleStyle()
      {
          Color colorBackground = ScreenUtil.getColor(ScreenUtil.BACKGROUND_COLOR, null, properties);
          Color colorControl = ScreenUtil.getColor(ScreenUtil.CONTROL_COLOR, null, properties);
          Color colorText = ScreenUtil.getColor(ScreenUtil.TEXT_COLOR, null, properties);
          samplePanel.setBackground(colorBackground);
          if (colorBackground == null)
              samplePanel.setBackground(SystemColor.window);
          Font font = ScreenUtil.getFont(null, properties, true);
          sampleLabel.setFont(font);
          sampleTextField.setFont(font);
          sampleTextField.setBackground(colorControl);
          if (colorControl == null)
              sampleTextField.setBackground(SystemColor.text);
          sampleLabel.setForeground(colorText);
          if (colorText == null)
              sampleLabel.setForeground(SystemColor.textText);
          sampleTextField.setForeground(colorText);
          if (colorText == null)
              sampleTextField.setForeground(SystemColor.textText);
  
          if (colorBackground != null)
              backgroundButton.setBackground(colorBackground);
          if (colorControl != null)
              controlColorButton.setBackground(colorControl);
          if (colorText != null)
              textColorButton.setBackground(colorText);
  
          this.invalidate();
      }
docs: Handle the button actions.