visual Studio 2017 扩充开发（一）《向Visual Studio菜单栏新增一个菜单》

<Buttons>
      <!--To define a menu group you have to specify its ID, the parent menu and its display priority.
          The command is visible and enabled by default. If you need to change the visibility, status, etc, you can use
          the CommandFlag node.
          You can add more than one CommandFlag node e.g.:
              <CommandFlag>DefaultInvisible</CommandFlag>
              <CommandFlag>DynamicVisibility</CommandFlag>
          If you do not want an image next to your command, remove the Icon node /> -->
      <Button guid="guidCommandPackageCmdSet" id="CommandId" priority="0x0100" type="Button">
        <Parent guid="guidCommandPackageCmdSet" id="MyMenuGroup" />
        <Icon guid="guidImages" id="bmpPic1" />
        <Strings>
          <ButtonText>测试菜单</ButtonText>
        </Strings>
      </Button>
    </Buttons>

        private void MenuItemCallback(object sender, EventArgs e)
        {
            string message = "Hello Word";
            string title = "测试";

            // Show a message box to prove we were here
            VsShellUtilities.ShowMessageBox(
                this.ServiceProvider,
                message,
                title,
                OLEMSGICON.OLEMSGICON_INFO,
                OLEMSGBUTTON.OLEMSGBUTTON_OK,
                OLEMSGDEFBUTTON.OLEMSGDEFBUTTON_FIRST);
        }