Lock application window to target form

[Ruku]

I remember back in vb6 I found some sample code that permited to lock notepad within an MDI child form on a project.

I'm looking for the exact same thing... but within vb .net and through a normal form.

I searched the forums and found

Private Declare Function LockWindowUpdate Lib "user32" Alias _
"LockWindowUpdate" (ByVal hwndLock As Long) As Long

which looks like a peace of the puzzle I need...

if anybody got pointers I'd appreciate... thx

EDIT: Oh and I'd also need the code to reverse the window back to it's original state...!