As I wanted to alter the captions of the standard Msgbox I had a look at the
Messagebox API and
after altering some code I found it seems this is working nicely. I know I
could use a Userform for
this, but I want to keep resources down and wasn't keen to add yet another
Userform to the project.

The only thing that is a slight problem is that the buttons don't resize
with the caption, but I can keep
the caption lenghth down.

The other thing is that this msgbox is modeless and that would seem a good
thing, but I am just wondering
if anybody is aware of any problems that could arise from this code:

Option Explicit

Private Const MB_YESNOCANCEL = &H3&
Private Const MB_YESNO = &H4&
Private Const MB_RETRYCANCEL = &H5&
Private Const MB_OKCANCEL = &H1&
Private Const MB_OK = &H0&
Private Const MB_ABORTRETRYIGNORE = &H2&
Private Const MB_ICONEXCLAMATION = &H30&
Private Const MB_ICONQUESTION = &H20&
Private Const MB_ICONASTERISK = &H40&
Private Const MB_ICONINFORMATION = MB_ICONASTERISK
Private Const IDOK = 1
Private Const IDCANCEL = 2
Private Const IDABORT = 3
Private Const IDRETRY = 4
Private Const IDIGNORE = 5
Private Const IDYES = 6
Private Const IDNO = 7
Private Const IDPROMPT = &HFFFF&
Private Const WH_CBT = 5
Private Const GWL_HINSTANCE = (-6)
Private Const HCBT_ACTIVATE = 5
Private Type MSGBOX_HOOK_PARAMS
 hwndOwner As Long
 hHook As Long
End Type
Private MSGHOOK As MSGBOX_HOOK_PARAMS
Private Declare Function GetCurrentThreadId Lib "kernel32" () As Long
Public Declare Function GetDesktopWindow Lib "user32" () As Long
Private Declare Function GetWindowLong Lib "user32" Alias _
                                      "GetWindowLongA" (ByVal hwnd As Long,
_
                                                        ByVal nIndex As
Long) As Long
Private Declare Function MessageBox Lib "user32" _
                                   Alias "MessageBoxA" (ByVal hwnd As Long,
_
                                                        ByVal lpText As
String, _
                                                        ByVal lpCaption As
String, _
                                                        ByVal wType As
Long) As Long
Private Declare Function SetDlgItemText _
                         Lib "user32" _
                             Alias "SetDlgItemTextA" (ByVal hDlg As Long, _
                                                      ByVal nIDDlgItem As
Long, _
                                                      ByVal lpString As
String) As Long
Private Declare Function SetWindowsHookEx _
                         Lib "user32" _
                             Alias "SetWindowsHookExA" (ByVal idHook As
Long, _
                                                        ByVal lpfn As Long,
_
                                                        ByVal hmod As Long,
_
                                                        ByVal dwThreadId As
Long) As Long
Private Declare Function SetWindowText _
                         Lib "user32" _
                             Alias "SetWindowTextA" (ByVal hwnd As Long, _
                                                     ByVal lpString As
String) As Long
Private Declare Function UnhookWindowsHookEx Lib "user32" _
                                            (ByVal hHook As Long) As Long
Private mbFlags As VbMsgBoxStyle
Private mbFlags2 As VbMsgBoxStyle
Private mTitle As String
Private mPrompt As String
Private But1 As String
Private But2 As String
Private But3 As String

Function FARPROC(ByVal pfn As Long) As Long

   'Procedure that receives and returns
   'the passed value of the AddressOf operator.

   'This workaround is needed as you can't assign
   'AddressOf directly to a member of a user-
   'defined type, but you can assign it to another
   'long and use that (as returned here)
   FARPROC = pfn

End Function

Function MessageBoxH(hwndThreadOwner As Long, _
                    hwndOwner As Long, _
                    mbFlags As VbMsgBoxStyle, _
                    strTitle As String, _
                    strPrompt As String) As Long

 'This function calls the hook
 Dim hInstance As Long
 Dim hThreadId As Long

 hInstance = GetWindowLong(hwndThreadOwner, GWL_HINSTANCE)
 hThreadId = GetCurrentThreadId()

 With MSGHOOK
   .hwndOwner = hwndOwner
   .hHook = SetWindowsHookEx(WH_CBT, _
                             FARPROC(AddressOf MsgBoxHookProc), _
                             hInstance, _
                             hThreadId)
 End With

 MessageBoxH = MessageBox(hwndOwner, _
                          strPrompt, _
                          strTitle, _
                          mbFlags)

End Function

Function MsgBoxHookProc(ByVal uMsg As Long, _
                       ByVal wParam As Long, _
                       ByVal lParam As Long) As Long

 'This function catches the messagebox before it opens
 'and changes the text of the buttons - then removes the hook
 If uMsg = HCBT_ACTIVATE Then
   SetWindowText wParam, mTitle
   SetDlgItemText wParam, IDPROMPT, mPrompt
   Select Case mbFlags
     Case vbAbortRetryIgnore, _
          vbAbortRetryIgnore + vbDefaultButton1, _
          vbAbortRetryIgnore + vbDefaultButton2, _
          vbAbortRetryIgnore + vbDefaultButton3
       SetDlgItemText wParam, IDABORT, But1
       SetDlgItemText wParam, IDRETRY, But2
       SetDlgItemText wParam, IDIGNORE, But3
     Case vbYesNoCancel, _
          vbYesNoCancel + vbDefaultButton1, _
          vbYesNoCancel + vbDefaultButton2, _
          vbYesNoCancel + vbDefaultButton3
       SetDlgItemText wParam, IDYES, But1
       SetDlgItemText wParam, IDNO, But2
       SetDlgItemText wParam, IDCANCEL, But3
     Case vbOKOnly
       SetDlgItemText wParam, IDOK, But1
     Case vbRetryCancel, _
          vbRetryCancel + vbDefaultButton1, _
          vbRetryCancel + vbDefaultButton2
       SetDlgItemText wParam, IDRETRY, But1
       SetDlgItemText wParam, IDCANCEL, But2
     Case vbYesNo, _
          vbYesNo + vbDefaultButton1, _
          vbYesNo + vbDefaultButton2
       SetDlgItemText wParam, IDYES, But1
       SetDlgItemText wParam, IDNO, But2
     Case vbOKCancel, _
          vbOKCancel + vbDefaultButton1, _
          vbOKCancel + vbDefaultButton2
       SetDlgItemText wParam, IDOK, But1
       SetDlgItemText wParam, IDCANCEL, But2
   End Select

   UnhookWindowsHookEx MSGHOOK.hHook
 End If

 MsgBoxHookProc = False

End Function

Function APIMsgBox(lHwnd As Long, _
                 mMsgbox As VbMsgBoxStyle, _
                 strTitle As String, _
                 strPrompt As String, _
                 Optional mMsgIcon As VbMsgBoxStyle, _
                 Optional strButA As String, _
                 Optional strButB As String, _
                 Optional strButC As String) As String

 'This function sets your custom parameters and returns
 'which button was pressed as a string
 Dim mReturn As Long

 mbFlags = mMsgbox
 mbFlags2 = mMsgIcon
 mTitle = strTitle
 mPrompt = strPrompt
 But1 = strButA
 But2 = strButB
 But3 = strButC

 mReturn = MessageBoxH(lHwnd, _
                       GetDesktopWindow(), _
                       mbFlags Or mbFlags2, _
                       strTitle, _
                       strPrompt)

 Select Case mReturn
   Case IDABORT
     APIMsgBox = But1
   Case IDRETRY
     APIMsgBox = But2
   Case IDIGNORE
     APIMsgBox = But3
   Case IDYES
     APIMsgBox = But1
   Case IDNO
     APIMsgBox = But2
   Case IDCANCEL
     APIMsgBox = But3
   Case IDOK
     APIMsgBox = But1
 End Select

End Function

Sub Test()

 Dim strReturn As String

 strReturn = APIMsgBox(Application.hwnd, _
                    vbYesNoCancel + vbDefaultButton2, _
                    "Messagebox Title", _
                    "Messagebox Prompt", , _
                    "Button 1", _
                    "Button 2", _
                    "Button 3")

 MsgBox "You pressed " & strReturn

End Sub