Compilation problem, don't know why

[jacek]

Why is it not possible to use slots and signals over distinct threads as you told me ?

From Qt docs:
The Signals and Slots mechanism can be used in separate threads, as long as the rules for QObject based classes are followed. The Signals and Slots mechanism is synchronous: when a signal is emitted, all slots are called immediately. The slots are executed in the thread context that emitted the signal.
Warning: Slots that generate window system events or use window system functions must not be connected to a signal that is emitted from a thread that is not the GUI thread. See the Qt Library Mutex section above for more details.

This says you can use them under certain conditions, but this:

None of the QObject based classes included in the Qt library are reentrant. [...] QObject and all of its subclasses are not thread-safe.

says that you probably won't be able to meet those conditions.

If you want to use signals & slots across threads, switch to Qt4 and use queued connections.

[yellowmat]

This is a great pleasure to chat with the Qt master you are

I hope that one day I will be able to help newbies like you do.