code: public void setToolDefault(int tool, boolean enabled) {
          switch (tool) {
              case IBurpExtenderCallbacks.TOOL_PROXY:
                  if (mCallbacks.loadExtensionSetting(SETTING_PROXY) == null) {
                      jCheckBoxProxy.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_REPEATER:
                  if (mCallbacks.loadExtensionSetting(SETTING_REPEATER) == null) {
                      jCheckBoxRepeater.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_SCANNER:
                  if (mCallbacks.loadExtensionSetting(SETTING_SCANNER) == null) {
                      jCheckBoxScanner.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_INTRUDER:
                  if (mCallbacks.loadExtensionSetting(SETTING_INTRUDER) == null) {
                      jCheckBoxIntruder.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_SEQUENCER:
                  if (mCallbacks.loadExtensionSetting(SETTING_SEQUENCER) == null) {
                      jCheckBoxProxy.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_SPIDER:
                  if (mCallbacks.loadExtensionSetting(SETTING_SPIDER) == null) {
                      jCheckBoxSpider.setSelected(enabled);
                  }
                  break;
              case IBurpExtenderCallbacks.TOOL_EXTENDER:
                  if (mCallbacks.loadExtensionSetting(SETTING_EXTENDER) == null) {
                      jCheckBoxExtender.setSelected(enabled);
                  }
                  break;
              default:
                  break;
          }
      }
docs: Allows the developer to set the default value for selected tools, not
  every tool makes sense for every extension
  
  @param tool The tool code, as defined in IBurpExtenderCallbacks
  @param enabled True if the checkbox should be checked by default.