[Signals and slots] handling of default arguments in SIGNAL macro

The behaviour of the SIGNAL macro regarding default arguments is not explicitely described, even though it's widely used in examples and demos.
if a signal has a default argument, for instance:
void f(bool = true);

then it is possible to use the SIGNAL macro with f() in QObject::Connect.

This could be documented in the general signals and slots documentation here:
http://doc.trolltech.com/4.5/signalsandslots.html