Code (Modul)

#If Win64 Then
    Private Type POINTAPI
       XY As LongLong
    End Type
#Else
    Private Type POINTAPI
           X As Long
           Y As Long
    End Type
#End If

Private Type MOUSEHOOKSTRUCT
    Pt As POINTAPI
    hWnd As Long
    wHitTestCode As Long
    dwExtraInfo As Long
End Type

#If VBA7 Then
    Private Declare PtrSafe Function FindWindow Lib "user32" _
                                            Alias "FindWindowA" ( _
                                                            ByVal lpClassName As String, _
                                                            ByVal lpWindowName As String) As LongPtr
    #If Win64 Then
        Private Declare PtrSafe Function GetWindowLongPtr Lib "user32" _
                                            Alias "GetWindowLongPtrA" ( _
                                                            ByVal hWnd As LongPtr, _
                                                            ByVal nIndex As Long) As LongPtr
    #Else
        Private Declare PtrSafe Function GetWindowLong Lib "user32" _
                                            Alias "GetWindowLongA" ( _
                                                            ByVal hWnd As LongPtr, _
                                                            ByVal nIndex As Long) As LongPtr
    #End If
    Private Declare PtrSafe Function SetWindowsHookEx Lib "user32" _
                                            Alias "SetWindowsHookExA" ( _
                                                            ByVal idHook As Long, _
                                                            ByVal lpfn As LongPtr, _
                                                            ByVal hmod As LongPtr, _
                                                            ByVal dwThreadId As Long) As LongPtr
    Private Declare PtrSafe Function CallNextHookEx Lib "user32" ( _
                                                            ByVal hHook As LongPtr, _
                                                            ByVal nCode As Long, _
                                                            ByVal wParam As LongPtr, _
                                                           lParam As Any) As LongPtr
    Private Declare PtrSafe Function UnhookWindowsHookEx Lib "user32" ( _
                                                            ByVal hHook As LongPtr) As LongPtr
    #If Win64 Then
        Private Declare PtrSafe Function WindowFromPoint Lib "user32" ( _
                                                            ByVal Point As LongLong) As LongPtr
    #Else
        Private Declare PtrSafe Function WindowFromPoint Lib "user32" ( _
                                                            ByVal xPoint As Long, _
                                                            ByVal yPoint As Long) As LongPtr
    #End If
    Private Declare PtrSafe Function GetCursorPos Lib "user32" ( _
                                                            ByRef lpPoint As POINTAPI) As LongPtr
#Else
    Private Declare Function FindWindow Lib "user32" _
                                            Alias "FindWindowA" ( _
                                                            ByVal lpClassName As String, _
                                                            ByVal lpWindowName As String) As Long
    Private Declare Function GetWindowLong Lib "user32.dll" _
                                            Alias "GetWindowLongA" ( _
                                                            ByVal hWnd As Long, _
                                                            ByVal nIndex As Long) 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 CallNextHookEx Lib "user32" ( _
                                                            ByVal hHook As Long, _
                                                            ByVal nCode As Long, _
                                                            ByVal wParam As Long, _
                                                           lParam As Any) As Long
    Private Declare Function UnhookWindowsHookEx Lib "user32" ( _
                                                            ByVal hHook As Long) As Long
    Private Declare Function WindowFromPoint Lib "user32" ( _
                                                            ByVal xPoint As Long, _
                                                            ByVal yPoint As Long) As Long
    Private Declare Function GetCursorPos Lib "user32.dll" ( _
                                                            ByRef lpPoint As POINTAPI) As Long
#End If

Private Const WH_MOUSE_LL As Long = 14
Private Const WM_MOUSEWHEEL As Long = &H20A
Private Const HC_ACTION As Long = 0
Private Const GWL_HINSTANCE As Long = (-6)
Dim n As Long
Private mCtl As Object
Private mbHook As Boolean

Const scrollOnly As Boolean = True ' False: Move Selection

#If VBA7 Then
    Private mLngMouseHook As LongPtr
    Private mListBoxHwnd As LongPtr
#Else
    Private mLngMouseHook As Long
    Private mListBoxHwnd As Long
#End If
     
Sub HookListBoxScroll(frm As Object, ctl As Object)
' Code by Peter Thornton (https://social.msdn.microsoft.com/Forums/en-US/9255d7d6-0266-45aa-9589-7533bd82d591/need-help-with-macro-to-make-an-userform-able-to-scroll-with-a-mouse?forum=isvvba)
    Dim tPT As POINTAPI
    #If VBA7 Then
        Dim lngAppInst As LongPtr
        Dim hwndUnderCursor As LongPtr
    #Else
        Dim lngAppInst As Long
        Dim hwndUnderCursor As Long
    #End If
    GetCursorPos tPT
    #If Win64 Then
        hwndUnderCursor = WindowFromPoint(tPT.XY)
    #Else
        hwndUnderCursor = WindowFromPoint(tPT.X, tPT.Y)
    #End If
    If TypeOf ctl Is UserForm Then
        If Not frm Is ctl Then
               ctl.SetFocus
        End If
    Else
        If Not frm.ActiveControl Is ctl Then
             ctl.SetFocus
        End If
    End If
    If mListBoxHwnd <> hwndUnderCursor Then
        UnhookListBoxScroll
        Set mCtl = ctl
        mListBoxHwnd = hwndUnderCursor
        #If Win64 Then
            lngAppInst = GetWindowLongPtr(mListBoxHwnd, GWL_HINSTANCE)
        #Else
            lngAppInst = GetWindowLong(mListBoxHwnd, GWL_HINSTANCE)
        #End If
        If Not mbHook Then
            mLngMouseHook = SetWindowsHookEx( _
                                            WH_MOUSE_LL, AddressOf MouseProc, lngAppInst, 0)
            mbHook = mLngMouseHook <> 0
        End If
    End If
End Sub

Sub UnhookListBoxScroll()
    If mbHook Then
        Set mCtl = Nothing
        UnhookWindowsHookEx mLngMouseHook
        mLngMouseHook = 0
        mListBoxHwnd = 0
        mbHook = False
    End If
End Sub
#If VBA7 Then
    Private Function MouseProc( _
                            ByVal nCode As Long, ByVal wParam As Long, _
                            ByRef lParam As MOUSEHOOKSTRUCT) As LongPtr
        Dim idx As Long
        On Error GoTo errH
        If (nCode = HC_ACTION) Then
            #If Win64 Then
                If WindowFromPoint(lParam.Pt.XY) = mListBoxHwnd Then
                    If wParam = WM_MOUSEWHEEL Then
                        MouseProc = True
                        If TypeOf mCtl Is Frame Then
                            If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                            idx = idx + mCtl.ScrollTop
                            If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then 
                                mCtl.ScrollTop = idx 
                            End If 
                        ElseIf TypeOf mCtl Is UserForm Then 
                            If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                            idx = idx + mCtl.ScrollTop
                            If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then 
                                mCtl.ScrollTop = idx 
                            End If 
                        Else 
                            If lParam.hWnd > 0 Then idx = -1 Else idx = 1
                            If scrollOnly Then
                                idx = idx + mCtl.TopIndex
                                If idx >= 0 Then mCtl.TopIndex = idx
                            Else
                                idx = idx + mCtl.ListIndex
                                If idx >= 0 Then mCtl.ListIndex = idx
                            End If
                        End If
                    Exit Function
                    End If
                Else
                    UnhookListBoxScroll
                End If
            #Else
                If WindowFromPoint(lParam.Pt.X, lParam.Pt.Y) = mListBoxHwnd Then
                    If wParam = WM_MOUSEWHEEL Then
                        MouseProc = True
                        If TypeOf mCtl Is Frame Then
                            If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                            idx = idx + mCtl.ScrollTop
                            If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then
                                mCtl.ScrollTop = idx 
                            End If 
                        ElseIf TypeOf mCtl Is UserForm Then 
                            If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                            idx = idx + mCtl.ScrollTop
                            If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then 
                                mCtl.ScrollTop = idx 
                            End If 
                        Else 
                            If lParam.hWnd > 0 Then idx = -1 Else idx = 1
                            If scrollOnly Then
                                idx = idx + mCtl.TopIndex
                                If idx >= 0 Then mCtl.TopIndex = idx
                            Else
                                idx = idx + mCtl.ListIndex
                                If idx >= 0 Then mCtl.ListIndex = idx
                            End If
                        End If
                        Exit Function
                    End If
                Else
                    UnhookListBoxScroll
                End If
            #End If
        End If
        MouseProc = CallNextHookEx( _
                                mLngMouseHook, nCode, wParam, ByVal lParam)
        Exit Function
errH:
        UnhookListBoxScroll
    End Function
#Else
    Private Function MouseProc( _
                            ByVal nCode As Long, ByVal wParam As Long, _
                            ByRef lParam As MOUSEHOOKSTRUCT) As Long
        Dim idx As Long
        On Error GoTo errH
        If (nCode = HC_ACTION) Then
            If WindowFromPoint(lParam.Pt.X, lParam.Pt.Y) = mListBoxHwnd Then
                If wParam = WM_MOUSEWHEEL Then
                    MouseProc = True
                    If TypeOf mCtl Is Frame Then
                        If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                        idx = idx + mCtl.ScrollTop
                        If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then 
                            mCtl.ScrollTop = idx 
                        End If 
                    ElseIf TypeOf mCtl Is UserForm Then 
                        If lParam.hWnd > 0 Then idx = -10 Else idx = 10
                        idx = idx + mCtl.ScrollTop
                        If idx >= 0 And idx < ((mCtl.ScrollHeight - mCtl.Height) + 17.25) Then 
                            mCtl.ScrollTop = idx 
                        End If 
                    Else 
                        If lParam.hWnd > 0 Then idx = -1 Else idx = 1
                        If scrollOnly Then
                            idx = idx + mCtl.TopIndex
                            If idx >= 0 Then mCtl.TopIndex = idx
                        Else
                            idx = idx + mCtl.ListIndex
                            If idx >= 0 Then mCtl.ListIndex = idx
                        End If
                    End If
                    Exit Function
                End If
            Else
                UnhookListBoxScroll
            End If
        End If
        MouseProc = CallNextHookEx( _
        mLngMouseHook, nCode, wParam, ByVal lParam)
        Exit Function
errH:
        UnhookListBoxScroll
    End Function
#End If

Code (UserForm)

Private Sub ListBox1_MouseMove(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single)

Call HookListBoxScroll(Me, Me.ListBox1)

End Sub

Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)

Call UnhookListBoxScroll

End Sub