' === Form relativ zur Referenzform positionieren, dabei Monitorgrenzen 
' beachten ===
Public Sub PositionFormRelativeToForm(ByVal frmToMove As Form, ByVal _
  referenceForm As Form, ByVal position As String, Optional ByVal spacing As _
  Long = 10)
    Dim refLeft As Long
    Dim refTop As Long
    Dim refWidth As Long
    Dim refHeight As Long
    Dim winWidth As Long
    Dim winHeight As Long
    Dim newLeft As Long
    Dim newTop As Long
 
    Dim hMonitor As Long
    Dim mi As MONITORINFO
    Dim monitorLeft As Long
    Dim monitorTop As Long
    Dim monitorWidth As Long
    Dim monitorHeight As Long
 
    ' Monitor bestimmen
    hMonitor = MonitorFromWindow(referenceForm.hWnd, MONITOR_DEFAULTTONEAREST)
    mi.cbSize = Len(mi)
    If GetMonitorInfo(hMonitor, mi) <> 0 Then
        monitorLeft = mi.rcWork.Left
        monitorTop = mi.rcWork.Top
        monitorWidth = mi.rcWork.Right - mi.rcWork.Left
        monitorHeight = mi.rcWork.Bottom - mi.rcWork.Top
    Else
        ' Falls fehlgeschlagen, gesamten Bildschirm nutzen
        monitorLeft = 0
        monitorTop = 0
        monitorWidth = Screen.Width \ Screen.TwipsPerPixelX
        monitorHeight = Screen.Height \ Screen.TwipsPerPixelY
    End If
 
    ' Referenz-Form-Koordinaten in Pixel
    refLeft = referenceForm.Left \ Screen.TwipsPerPixelX
    refTop = referenceForm.Top \ Screen.TwipsPerPixelY
    refWidth = referenceForm.Width \ Screen.TwipsPerPixelX
    refHeight = referenceForm.Height \ Screen.TwipsPerPixelY
 
    ' Ziel-Form-Größe in Pixel
    winWidth = frmToMove.Width \ Screen.TwipsPerPixelX
    winHeight = frmToMove.Height \ Screen.TwipsPerPixelY
 
    ' Grundposition berechnen
    Select Case LCase(position)
        Case "right"
            newLeft = refLeft + refWidth + spacing
            newTop = refTop + (refHeight - winHeight) \ 2
        Case "left"
            newLeft = refLeft - winWidth - spacing
            newTop = refTop + (refHeight - winHeight) \ 2
        Case "below"
            newLeft = refLeft + (refWidth - winWidth) \ 2
            newTop = refTop + refHeight + spacing
        Case "above"
            newLeft = refLeft + (refWidth - winWidth) \ 2
            newTop = refTop - winHeight - spacing
        Case "center"
            newLeft = refLeft + (refWidth - winWidth) \ 2
            newTop = refTop + (refHeight - winHeight) \ 2
        Case Else
            newLeft = refLeft + (refWidth - winWidth) \ 2
            newTop = refTop + (refHeight - winHeight) \ 2
    End Select
 
    ' === Begrenzen auf Monitor-Arbeitsbereich ===
    If newLeft < monitorLeft Then newLeft = monitorLeft
    If newTop < monitorTop Then newTop = monitorTop
    If newLeft + winWidth > monitorLeft + monitorWidth Then
        newLeft = monitorLeft + monitorWidth - winWidth
    End If
    If newTop + winHeight > monitorTop + monitorHeight Then
        newTop = monitorTop + monitorHeight - winHeight
    End If
 
    ' Position setzen
    Call SetWindowPos(frmToMove.hWnd, 0, newLeft, newTop, 0, 0, _
                      SWP_NOSIZE Or SWP_NOZORDER Or SWP_NOACTIVATE)
End Sub