Binaryworld - RemoveCloseMenuItem - Remove the Close button and command from a form ... [ VB -> Forms & Controls ]

Private Declare Function GetSystemMenu Lib "user32" (ByVal hWnd As Long, _
  ByVal bRevert As Long) As Long
Private Declare Function RemoveMenu Lib "user32" (ByVal hMenu As Long, _
  ByVal nPosition As Long, ByVal wFlags As Long) As Long

' Remove the Close menu item and disable the Close button
' from a window

Public Sub RemoveCloseMenuItem(ByVal hWnd As Long)
  Const SC_CLOSE = &HF060
  Const MF_BYCOMMAND = 0

  Dim hMenu As Long
  ' get the system menu's handle
  hMenu = GetSystemMenu(hWnd, 0)
  ' remove the Close item
  RemoveMenu hMenu, SC_CLOSE, MF_BYCOMMAND
End Sub