modify a QML Text from C++

[anda_skoa]

> I am surprised that this works.
Why? Which part of the code is illogical?

You load the QML file before setting the context property but the QML code accesses the context property.
I would have expect that to cause the QML file to fail loading.

Usually one would set the context property before loading.

> In any case you should not call MyDisplay::setText()
Why?

It is OK now, I didn't see you had removed the usage of QThread.

> from the secondary thread
secondary thread? I did not use thread.

Right, you had thread usage earlier, didn't see that this changed.

That also makes the signal/slot approach unnecessary.

Since you are not using threading anymore you could even add the property to the MySerialPort class and set its instance as the context property.

Cheers,
_