A VFP DLL cannot have any UI. You could try writing to the event log.

>Hi everybody,
>
>I have a C++ Service application that calls VFP dll. In this dll we try to call Windows API Messagebox (the call to this messagebox is in the custom class).
>
>The call to the Messagebox is in the do while loop. The messagebox never gets displayed.
>
>Do you know if it's possible to call messagebox from the multi-threaded DLL that is called by the service?
>
>Thanks in advance.