ToolbarStyle = WS_CHILD Or WS_VISIBLE Or _
                TBSTYLE_TOOLTIPS...

'ToolTip Notification
Private Type NMTTDISPINFO
    hdr As NMHDR
    lpszText As Long
    szText( 0  To  79 ) As Byte
    hinst As Long
    uFlags As Long
    lParam As Long
End Type


Public Function NewToolBarWindowProc(ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
    Dim uNMHDR  As NMHDR
     Dim tT As NMTTDISPINFO
    Dim sToolTipBuffer As String
    Dim b() As Byte
    
    Select Case Msg
        Case WM_NOTIFY
            Call CopyMemory(uNMHDR, ByVal lParam, Len(uNMHDR))
            'Debug.Print uNMHDR.code
            Select Case uNMHDR.code
                Case TTN_GETDISPINFO
'                    Call CopyMemory(tT, ByVal lParam, Len(tT))
                    'Debug.Print "TTN_GETDISPINFO:" & tT.hdr.idFrom
                    sToolTipBuffer = "Test Tool Tip"
                    If (Len(sToolTipBuffer) >  0 ) Then
                        CopyMemory tT, ByVal lParam, Len(tT)
                        b = StrConv(sToolTipBuffer, vbFromUnicode)
                        ReDim b( 0  To UBound(b) +  1 ) As Byte
                        b(UBound(b)) =  0 
                        CopyMemory ByVal tT.lpszText, b( 0 ), UBound(b) +  1 
                        CopyMemory tT.szText( 0 ), b( 0 ), UBound(b) +  1 
                        tT.hinst =  0 
                        CopyMemory ByVal lParam, tT, Len(tT)
                        Debug.Print "TTN_GETDISPINFO:" & tT.hdr.idFrom
                        Exit Function
                    End If
'                    Select Case tT.hdr.idFrom
'                        Case 1
'                            tT.szText = MAKEINTRESOURCE(101)
'                        Case Else
'                    End Select
                Case Else
            End Select

Private Type NMTTDISPINFO
    hdr As NMHDR
    lpszText As Long
    'szText(0 To 79) As Byte
    szText As String *  80 
    hinst As Long
    uFlags As Long
    lParam As Long
End Type

'Private Type NMTTDISPINFO_SHORT
'    hdr      As NMHDR
'    lpszText As Long
'    szText   As String * 80
'    hinst    As Long
'    uFlags   As Long
'End Type

Private Type NMTTDISPINFO_SHORT
    hdr As NMHDR
    lpszText As Long
    szText( 0  To  79 ) As Byte
    hinst As Long
    uFlags As Long
End Type

Dim uNMTTDI As NMTTDISPINFO_SHORT
Dim s As String

Case TTN_GETDISPINFO
    s = "test"
    If Len(s) Then
        Call CopyMemory(uNMTTDI, ByVal lParam, Len(uNMTTDI))
        uNMTTDI.lpszText = StrPtr(StrConv(s, vbFromUnicode))
        Call CopyMemory(ByVal lParam, uNMTTDI, Len(uNMTTDI))
    End If

I find it
much simpler just to add static tip strings to the tooltip control and
let it manage the strings rather than deal with TTN_GETDISPINFO. Note
you need the individual button rect since they're not separate
windows. If it helps, here's a snip from a class that wraps a
ToolbarWindow32:

Private Sub GetBtnRect(ByVal idBtn As Long, ByRef rcBtn As RECT)
SendMessage m_hWnd, TB_GETRECT, idBtn, rcBtn
End Sub

Private Sub AddTip(ByVal ID As Long, sText As String)
'called by AddButton
Dim TI As TOOLINFO

GetBtnRect ID, TI.R

With TI
.cbSize = CLng(LenB(TI))
.uFlags = TTF_SUBCLASS
.hWnd = m_hWnd
.uId = ID
.lpszText = sText
End With
SendMessage m_hTips, TTM_ADDTOOL,  0 &, TI
End Sub

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" ( _
    lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)

        Case  512 
            Form1.Caption = "покинули"

 ' 'загрузка событий Toolbar
 OldReBarWindowProc = SetWindowLong(Me.hWnd, GWL_WNDPROC, _
    AddressOf NewReBarWindowProc)

                Case TTN_GETDISPINFO
                    s = "test"
                    If Len(s) Then
                        Call CopyMemory(uNMTTDI, ByVal lParam, Len(uNMTTDI))
                        s = "test" & uNMTTDI.hdr.idFrom
                        uNMTTDI.lpszText = StrPtr(StrConv(s, vbFromUnicode))
                        Call CopyMemory(ByVal lParam, uNMTTDI, Len(uNMTTDI))
                    End If

 With tbButtonsCreate( 1 )\n    .iBitmap = IDB_FORWARD\n    .idCommand =  2  \'IDM_GOFORWARD\n    \'.fsState = TBSTATE_ENABLED\n    .fsStyle = BTNS_BUTTON\n End With

        Case  512 \n            Form1.Caption = "покинули"