[Lazarus] Sending messages

Hans-Peter Diettrich DrDiettrich1 at aol.com
Fri Nov 25 10:35:42 CET 2011

Felipe Monteiro de Carvalho schrieb:
> On Thu, Nov 24, 2011 at 6:18 PM, Hans-Peter Diettrich
> <DrDiettrich1 at aol.com> wrote:
>> Q: does the LCL support more than one message queue (the one in
>> Application)?
> There are various event loops:
> * Application.Run
> * ShowModal makes a loop too
> * ProcessMessages has a short lived loop
> And user code can also start their own loops by using ProcessMessages

This doesn't answer my question. What's the *source* of the processed 

> I wouldn't call those loops "event queues", because they don't
> implement any kind of queues, they process all events which are
> obtained immediately. The events are not stored in queues. The queue
> itself is inside the backend library, for example Windows API, X11,
> etc.

So what happens on PostMessage, in detail when multiple threads post 
messages at the same time?

TWidgetSet.SendMessage and PostMessage are both documented as 
thread-safe. Is this correct, and if so, how is that ensured?
Does a SendMessage call bypass any other messages which have been queued 
until that time? (by dispatching the message immediately to the target?)

What happens in TWidgetset.PeekMessage?


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