Ordinarily it is quite a simple matter to disable a menu item, but VB does not like us doing this to a form's close button. As a result more work is required to trick VB into thinking that the close option no longer exists if we are to disable the button. This is all hidden from the developer in one simple function.
For example, to disable a form's close button on loading:
PrivateSub Form_Load() EnableCloseButton me.hWnd, false End Sub
And to re-enable it later:
private Sub Command1_Click() EnableCloseButton me.hWnd, true End Sub
EnableCloseButton() was written in VB6