VC++托盘应用教程：自定义对话框与简易实现

Let's go step-by-step. 
1. Build a tray application 

Here we are building a dialog-based application, which has a modeless dialog. So, create a new dialog-based MFC application (I've used Visual Studio 2005) with dialog class name CTrayMeDlg and application class name CTrayMeApp. Add a pointer variable *m_pApplicationDialog of CTrayMeDlg class in the application... 
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class CTrayMeApp: public CWinApp
{
    /* class code goes here */
    
    private:        
        CTrayMeDlg * m_pApplicationDialog;

};

...and replace the traditional DoModal code with the following in the InitInstance() of the application class, as shown below.
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BOOL CTrayMeApp::InitInstance()
{
    /* Function's default code goes here */

    //Create a invisible modless dialog.
    m_pApplicationDialog = new CTrayMeDlg();
    m_pApplicationDialog->Create(IDD_TRAYME_DIALOG,NULL);
    m_pMainWnd = m_pApplicationDialog;
      ShowWindow(m_pMainWnd->GetSafeHwnd(),SW_HIDE);

    return TRUE;

    /*
    CTrayMeDlg dlg;

    m_pMainWnd = &dlg;
    INT_PTR nResponse = dlg.DoModal();

    if (nResponse == IDOK)
    {
        // TODO: Place code here to handle when the dialog is
        //  dismissed with OK
    }
    else if (nResponse == IDCANCEL)
    {
        // TODO: Place code here to handle when the dialog is
        //  dismissed with Cancel
    }

    // Since the dialog has been closed, return FALSE so that we exit the
    //  application, rather than start the application's message pump.
     return FALSE;
  */
}

You might have noticed the SW_HIDE parameter of ShowWindow(). We aren't going to show any dialog as we are building a tray application. All the UI we have for the application is just the context menu of the tray icon. Shell_NotifyIcon() is the API to deal with the application's system tray icon. It sends the message to the system tray to add, modify or delete the icon from the taskbar status area. The following code from OnInitDialog() of CTrayMeDlg makes the system add an application notification icon into the taskbar's status area. 
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BOOL CTrayMeDlg::OnInitDialog()
{
    /* Function's default code goes here*/
    // TODO: Add extra initialization here
    
    //Add a Tray Notification Icon for the application.

    NOTIFYICONDATA niData;