Private mobjSysBtn As CommandBarPopup

Private Type POINTAPI
   x As Long
   y As Long
End Type

Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type

Private Declare Function GetCursorPos Lib "user32.dll" (ByRef lpPoint As POINTAPI) As Long
Private Declare Function ScreenToClient Lib "user32.dll" (ByVal hwnd As Long, ByRef lpPoint As POINTAPI) As Long
Private Declare Function PtInRect Lib "user32.dll" (ByRef lpRect As RECT, ByVal x As Long, ByVal y As Long) As Long

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
   Dim udtPoint As POINTAPI
   Dim udtRect As RECT
   
   With udtRect
      mobjSysBtn.GetRect .Left, .Top, .Right, .Bottom   ' Get the position of the SystemButton
   End With
   
   If UnloadMode = vbFormControlMenu Then
      GetCursorPos udtPoint    ' Get the position of the mouse pointer
      ScreenToClient Me.hwnd, udtPoint    ' Convert screen coordinates to coordinates relative to the form with the SystemButton
      
      Cancel = PtInRect(udtRect, udtPoint.x, udtPoint.y)    ' Only cancel unloading if the mouse pointer is not above the SystemButton
   End If
End Sub