MFC: Adding tray icon to the window

main.cpp

#include <stdafx.h>
...

// tray icon ID
#define ID_SYSTEMTRAY 0x1000

// custom message ID
#define WM_TRAYICON_EVENT (WM_APP + 1)

// tray icon resource ID
#define ID_ICON_TRAY_INITIAL 0x2000

class CMyDlg : public CDialog
{ 
 ...
protected:
 // tray icon data
 NOTIFYICONDATA m_NID;

 CPoint m_ptMouseHoverEvent;
 
 // adds icon to the system tray
 BOOL CreateTrayIcon();

 // displays rectangular tip
 BOOL SetTrayIconTipText(LPCTSTR pszText);

 // displays baloon notification
 // unTimeout is in milliseconds
 BOOL ShowTrayIconBalloon(LPCTSTR pszTitle, LPCTSTR pszText, UINT unTimeout, DWORD dwInfoFlags);

 // sets icon resource
 BOOL SetTrayIcon(HICON hIcon);

 // sets icon resource
 BOOL SetTrayIcon(WORD wIconID);

 // removes icon from tray
 BOOL DestroyTrayIcon();

 ...
 // WM_INITDIALOG handler
 virtual BOOL OnInitDialog();

 // WM_DESTROY handler
 afx_msg void OnDestroy();

 // WM_TRAYICON_EVENT handler
 afx_msg LRESULT OnTrayIconEvent(WPARAM wParam, LPARAM lParam);
};

BOOL CMyDlg::CreateTrayIcon()
{  
  memset(&m_NID, 0 , sizeof(m_NID));
  m_NID.cbSize = sizeof(m_NID);

  // set tray icon ID
  m_NID.uID = ID_SYSTEMTRAY;

  // set handle to the window that receives tray icon notifications
  ASSERT(::IsWindow(GetSafeHwnd()));
  m_NID.hWnd = GetSafeHwnd();

  // set message that will be sent from tray icon to the window 
  m_NID.uCallbackMessage = WM_TRAYICON_EVENT;

  // fields that are being set when adding tray icon 
  m_NID.uFlags = NIF_MESSAGE|NIF_ICON; 

  // set image
  m_NID.hIcon = LoadIcon(AfxGetInstanceHandle(), MAKEINTRESOURCE(ID_ICON_TRAY_INITIAL));

  if(!m_NID.hIcon)
    return FALSE;

  m_NID.uVersion = NOTIFYICON_VERSION_4;

  if(!Shell_NotifyIcon(NIM_ADD, &m_NID))
    return FALSE;

  return Shell_NotifyIcon(NIM_SETVERSION, &m_NID);
}

BOOL CMyDlg::DestroyTrayIcon()
{
  return Shell_NotifyIcon(NIM_DELETE, &m_NID); 
}

BOOL CMyDlg::SetTrayIconTipText(LPCTSTR pszText)
{
  if(StringCchCopy(m_NID.szTip, sizeof(m_NID.szTip), pszText) != S_OK)
    return FALSE;
 
  m_NID.uFlags |= NIF_TIP;
  return Shell_NotifyIcon(NIM_MODIFY, &m_NID); 
}

BOOL CMyDlg::ShowTrayIconBalloon(LPCTSTR pszTitle, LPCTSTR pszText, UINT unTimeout, DWORD dwInfoFlags)
{  
  m_NID.uFlags |= NIF_INFO;
  m_NID.uTimeout = unTimeout;
  m_NID.dwInfoFlags = dwInfoFlags;

  if(StringCchCopy(m_NID.szInfoTitle, sizeof(m_NID.szInfoTitle), pszTitle) != S_OK)
    return FALSE;

  if(StringCchCopy(m_NID.szInfo, sizeof(m_NID.szInfo), pszText) != S_OK)
    return FALSE;

  return Shell_NotifyIcon(NIM_MODIFY, &m_NID);
}

BOOL CMyDlg::SetTrayIcon(HICON hIcon)
{
  m_NID.hIcon = hIcon;
  m_NID.uFlags |= NIF_ICON;

  return Shell_NotifyIcon(NIM_MODIFY, &m_NID); 
}

BOOL CMyDlg::SetTrayIcon(WORD wIconID)
{
  HICON hIcon = LoadIcon(AfxGetInstanceHandle(), MAKEINTRESOURCE(wIconID));

  if(!hIcon) 
    return FALSE;

  return SetTrayIcon(hIcon);
}

BEGIN_MESSAGE_MAP(CMyDlg, CDialog)
  ...
  ON_MESSAGE(WM_TRAYICON_EVENT, OnTrayIconEvent)
  ...
END_MESSAGE_MAP()

BOOL CMyDlg::OnInitDialog()
{
  CDialog::OnInitDialog();
  ...
  CreateTrayIcon();

  // Add following line in order to enable tip from the beginning.
  // Tip shows automatically each time mouse pointer is over tray icon.
  SetTrayIconTipText(TEXT("Initial tip text"));
  ...
  return TRUE; 
}

void CMyDlg::OnDestroy()
{
  ...
  DestroyTrayIcon();
  ...
  CDialog::OnDestroy();
}

LRESULT CMyDlg::OnTrayIconEvent(WPARAM wParam, LPARAM lParam)
{ 
  if((UINT)wParam != ID_SYSTEMTRAY)
    return ERROR_SUCCESS;
  
  switch((UINT)lParam) 
  {   
    case WM_MOUSEMOVE:      
      {
        // do something
        // e.g. save mouse position in time of event
        GetCursorPos(&m_ptMouseHoverEvent);
        ... 
        break;  
      }
    case WM_LBUTTONUP:
    {    
      // e.g. show main dialog or set (new) tip text and display baloon:

      CTime timeCurr = CTime::GetCurrentTime();
      CString strTimeCurr;
      strTimeCurr.Format(TEXT("%d:%d:%d"), timeCurr.GetHour(), timeCurr.GetMinute(), timeCurr.GetSecond());
      CString strText(TEXT("This text was set at "));
      strText += strTimeCurr;    

      SetTrayIconTipText((LPCTSTR)strText);
    
      ShowTrayIconBalloon(TEXT("Baloon message title"), TEXT("Left click!"), 1000, NIIF_INFO);

      break;
    }   
    case WM_RBUTTONUP:
    {
      // e.g. show context menu or disable tip and display baloon:

      SetTrayIconTipText((LPCTSTR)TEXT(""));    
      ShowTrayIconBalloon(TEXT("Baloon message title"), TEXT("Right click!"), 1000, NIIF_INFO);
      break;
    }   
  }

  return ERROR_SUCCESS;
}

I have changed the code to use if (_tcscpy_s(m_NID.szTip, m_strTrayIconTip) != S_OK).