The function you should use is Application.ProcessMessages.
There is also an API function called Yield that seems to do the same thing, but it isn't safe
to use from most Delphi applications.
Steve Teixeira explains:
"You should not use Yield() unless your application is *guaranteed* not
to receive any messages (ie, your application contains no windows).
Instead, the way to do this in Delphi is to call Application.ProcessMessages.
ProcessMessage encapsulates a PeekMessage() loop, which is the correct "API-way" to do this."