Declares:
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'SysTray Icon
Private Type GUID
   Data1 As Long
   Data2 As Integer
   Data3 As Integer
   Data4(7) As Byte
End Type

' Type passed to Shell_NotifyIcon
Private Type NOTIFYICONDATA
  Size As Long
  Handle As Long
  ID As Long
  Flags As Long
  CallBackMessage As Long
  Icon As Long
  Tip As String * 128
  dwState As Long
  dwStateMask As Long
  szInfo As String * 256
  uTimeoutAndVersion As Long
  szInfoTitle As String * 64
  dwInfoFlags As Long
  guidItem As GUID
End Type

' Constants for managing System Tray tasks, found in shellapi.h
Private Const AddIcon = &H0
Private Const ModifyIcon = &H1
Private Const DeleteIcon = &H2

Private Const WM_MOUSEMOVE = &H200
Private Const WM_LBUTTONDBLCLK = &H203
Private Const WM_LBUTTONDOWN = &H201
Private Const WM_LBUTTONUP = &H202

Private Const WM_RBUTTONDBLCLK = &H206
Private Const WM_RBUTTONDOWN = &H204
Private Const WM_RBUTTONUP = &H205

Private Const MessageFlag = &H1
Private Const IconFlag = &H2
Private Const TipFlag = &H4
'''
Private Const APP_SYSTRAY_ID = 999 'unique identifier
Private Const NOTIFYICON_VERSION = &H3
Private Const NIF_MESSAGE = &H1
Private Const NIF_ICON = &H2
Private Const NIF_TIP = &H4
Private Const NIF_STATE = &H8
Private Const NIF_INFO = &H10
Private Const NIM_ADD = &H0
Private Const NIM_MODIFY = &H1
Private Const NIM_DELETE = &H2
Private Const NIM_SETFOCUS = &H3
Private Const NIM_SETVERSION = &H4
Private Const NIM_VERSION = &H5
Private Const NIS_HIDDEN = &H1
Private Const NIS_SHAREDICON = &H2

'shell version / NOTIFIYICONDATA struct size constants
Private Const NOTIFYICONDATA_V1_SIZE As Long = 88  'pre-5.0 structure size
Private Const NOTIFYICONDATA_V2_SIZE As Long = 488 'pre-6.0 structure size
Private Const NOTIFYICONDATA_V3_SIZE As Long = 504 '6.0+ structure size
Private NOTIFYICONDATA_SIZE As Long

'icon flags
Private Const NIIF_NONE = &H0
Private Const NIIF_INFO = &H1
Private Const NIIF_WARNING = &H2
Private Const NIIF_ERROR = &H3
Private Const NIIF_GUID = &H5
Private Const NIIF_ICON_MASK = &HF
Private Const NIIF_NOSOUND = &H10
   
Private Const WM_USER = &H400
Private Const NIN_BALLOONSHOW = (WM_USER + 2)
Private Const NIN_BALLOONHIDE = (WM_USER + 3)
Private Const NIN_BALLOONTIMEOUT = (WM_USER + 4)
Private Const NIN_BALLOONUSERCLICK = (WM_USER + 5)

Private Data As NOTIFYICONDATA
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, lpdwProcessId As Long) As Long
Private Declare Function SetCapture Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function Shell_NotifyIcon Lib "shell32" Alias "Shell_NotifyIconA" (ByVal dwMessage As Long, lpData As NOTIFYICONDATA) As Boolean
Private Declare Function GetFileVersionInfoSize Lib "version.dll" Alias "GetFileVersionInfoSizeA" (ByVal lptstrFilename As String, lpdwHandle As Long) As Long
Private Declare Function GetFileVersionInfo Lib "version.dll" Alias "GetFileVersionInfoA" (ByVal lptstrFilename As String, ByVal dwHandle As Long, ByVal dwLen As Long, lpData As Any) As Long
Private Declare Function VerQueryValue Lib "version.dll" Alias "VerQueryValueA" (pBlock As Any, ByVal lpSubBlock As String, lpBuffer As Any, nVerSize As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
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User Code:
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AddIconToTray(sIconToolTip As String) 'The tooltip is displayed when the cursor hovers over the tray icon.
DisplayBallon(nIconIndex As Long, sTitle As String, sText As String) 'nIconIndex: 0=nothing, 1=info, 2=exclam, 3=critical
DeleteIconFromTray
'Note
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User Functions:
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Private Sub Form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)

  Dim message As Long
  message = X / Screen.TwipsPerPixelX

  Select Case message
    Case WM_LBUTTONDBLCLK
                ' "Left Button Double Click!"
                Me.Show
                DeleteIconFromTray
    Case WM_MOUSEMOVE
                ' "MouseMove!"
    Case WM_LBUTTONDOWN
                ' "Left MouseDown"
    Case WM_LBUTTONUP
                ' "Left MouseUp"
    Case WM_RBUTTONDOWN
                ' "Right MouseDown"
    Case WM_RBUTTONUP
                ' "Right MouseUp"
                PopupMenu mnuPopup
    Case WM_RBUTTONDBLCLK
                ' "Right Button Double Click!"
    End Select
End Sub
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Functions:
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Private Sub AddIconToTray(sIconToolTip As String)
Me.Hide
  If NOTIFYICONDATA_SIZE = 0 Then SetShellVersion
  Data.Size = NOTIFYICONDATA_SIZE 'Len(Data)
  Data.Handle = hwnd
  Data.ID = APP_SYSTRAY_ID 'vbNull
  Data.Flags = NIF_MESSAGE Or NIF_ICON Or NIF_TIP 'IconFlag Or TipFlag Or MessageFlag
  Data.CallBackMessage = WM_MOUSEMOVE
  Data.Icon = Icon
  Data.Tip = sIconToolTip & vbNullChar
  Data.dwState = NIS_SHAREDICON
  Data.uTimeoutAndVersion = NOTIFYICON_VERSION
  
  Call Shell_NotifyIcon(AddIcon, Data)
  Call Shell_NotifyIcon(NIM_SETVERSION, Data)
'''
   
  'add the icon ...
   'Call Shell_NotifyIcon(NIM_ADD, nid)
   
  '... and inform the system of the
  'NOTIFYICON version in use
   'Call Shell_NotifyIcon(NIM_SETVERSION, nid)
End Sub
'---------------------------------------------------------------------------------------
Private Sub DisplayBallon(nIconIndex As Long, sTitle As String, sText As String)
   'Dim nid As NOTIFYICONDATA use data
   If NOTIFYICONDATA_SIZE = 0 Then SetShellVersion
   With Data
      .Size = NOTIFYICONDATA_SIZE
      .Handle = hwnd
      .ID = APP_SYSTRAY_ID
      .Flags = NIF_INFO
      .dwInfoFlags = nIconIndex
      'InfoTitle is the balloon tip title,
      'and szInfo is the message displayed.
      'Terminate both with vbNullChar
      .szInfoTitle = sTitle & vbNullChar
      .szInfo = sText & vbNullChar
   End With

   Call Shell_NotifyIcon(NIM_MODIFY, Data)
End Sub
'---------------------------------------------------------------------------------------
Private Sub DeleteIconFromTray()
Me.Show
  Call Shell_NotifyIcon(DeleteIcon, Data)
  '''
 
   If NOTIFYICONDATA_SIZE = 0 Then SetShellVersion
      
   With Data
      .Size = NOTIFYICONDATA_SIZE
      .Handle = hwnd
      .ID = APP_SYSTRAY_ID
   End With
   
   'Call Shell_NotifyIcon(NIM_DELETE, nid)
End Sub
'---------------------------------------------------------------------------------------
Private Sub SetShellVersion()
   Select Case True
      Case IsShellVersion(6)
         NOTIFYICONDATA_SIZE = NOTIFYICONDATA_V3_SIZE '6.0+ structure size
      Case IsShellVersion(5)
         NOTIFYICONDATA_SIZE = NOTIFYICONDATA_V2_SIZE 'pre-6.0 structure size
      Case Else
         NOTIFYICONDATA_SIZE = NOTIFYICONDATA_V1_SIZE 'pre-5.0 structure size
   End Select
End Sub
'---------------------------------------------------------------------------------------
Private Function IsShellVersion(ByVal version As Long) As Boolean
  'returns True if the Shell version
  '(shell32.dll) is equal or later than
  'the value passed as 'version'
   Dim nBufferSize As Long
   Dim nUnused As Long
   Dim lpBuffer As Long
   Dim nVerMajor As Integer
   Dim bBuffer() As Byte
   Const sDLLFile As String = "shell32.dll"
   nBufferSize = GetFileVersionInfoSize(sDLLFile, nUnused)
   If nBufferSize > 0 Then
      ReDim bBuffer(nBufferSize - 1) As Byte
      Call GetFileVersionInfo(sDLLFile, 0&, nBufferSize, bBuffer(0))
      If VerQueryValue(bBuffer(0), "\", lpBuffer, nUnused) = 1 Then
         CopyMemory nVerMajor, ByVal lpBuffer + 10, 2
         IsShellVersion = nVerMajor >= version
      End If  'VerQueryValue
   End If  'nBufferSize
End Function
'---------------------------------------------------------------------------------------
Public Function AppHolok(ByVal idHook As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
    Dim CWP As CWPSTRUCT
    CopyMemory CWP, ByVal lParam, Len(CWP)
    Select Case CWP.message
        Case WM_CREATE
            SetForegroundWindow CWP.hwnd
            AppHook = CallNextHookEx(hHook, idHook, wParam, ByVal lParam)
            UnhookWindowsHookEx hHook
            hHook = 0
            Exit Function
    End Select
    AppHook = CallNextHookEx(hHook, idHook, wParam, ByVal lParam)
End Function
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