Need to disable\enable a Form's Close button
Here's a snippet that may help:
#Region " Enable\Disable a Form's Close Button "
Private Declare Function GetSystemMenu Lib "user32" (ByVal hwnd As Integer, ByVal revert As Integer) As Integer
Private Declare Function EnableMenuItem Lib "user32" (ByVal menu As Integer, ByVal ideEnableItem As Integer, ByVal enable As Integer) As Integer
Private Const SC_CLOSE As Integer = &HF060
Private Const MF_BYCOMMAND As Integer = &H0
Private Const MF_GRAYED As Integer = &H1
Private Const MF_ENABLED As Integer = &H0
Public Sub DisableFormCloseButton(ByVal form As System.Windows.Forms.Form)
' The return value specifies the previous state of the menu item (it is either
' MF_ENABLED or MF_GRAYED). 0xFFFFFFFF indicates that the menu item does not exist.
Select Case EnableMenuItem(GetSystemMenu(form.Handle.ToInt32, 0), SC_CLOSE, MF_BYCOMMAND Or MF_GRAYED)
Case MF_ENABLED
Case MF_GRAYED
Case &HFFFFFFFF
Throw New Exception("The Close menu item does not exist.")
Case Else
End Select
End Sub
Public Sub EnableFormCloseButton(ByVal form As System.Windows.Forms.Form)
EnableMenuItem(GetSystemMenu(form.Handle.ToInt32, 0), SC_CLOSE, MF_BYCOMMAND)
End Sub
#End Region
Credits to the source that helped me figure this out.