Ed,
That's really the difference in VFP then. Changing the LockScreen property does not call the LockWindowUpdate function at all. I have run Spy++ and verified that WM_PAINT messages are sent to the form. However, it is my belief that VFP's message handler checks the property when it receives a WM_PAINT message and ignores it. While using LockWindowUpdate causes these messages to be ignored at the OS level. It is for this reason that you can "lock" multiple forms in VFP and you can't in VB.

Thanks for the info about SetParent, etc.

>For VB, you should only have to LockWindowUpdate the parent. In VB, child controls are linked to the main forms Hwnd through internal SetParent() calls. In VFP, the VFP screens are bitmapped by the runtime engine, but message pump calls to OCX calls seem to be fed to the control (including WM_PAINT). That is probably a bug in VFP since the runtime knows the parent hwnd (which is the only native VFP control with a real hwnd) is locked, it shouldn't allow any WM_PAINT messages to child OCX controls.
>
>You would really have to watch Spy++ messages for those controls to be sure though.
>
>HTH,
>Ed
>