Question about implicit sharing

[Cruz]

I want to make sure I understand this right.

I have an implicitly shared container, say a QHash. Object A creates it and passes it to object B by value.

A
{
   QHash;
   B.takeThis(QHash);
}

A
{
   QHash;
   B.takeThis(QHash);
}

To copy to clipboard, switch view to plain text mode 

So far, when reading from the QHash both A and B would read from the same memory block, right?

Now A modifies the QHash.

A
{
   QHash;
   B.takeThis(QHash);
   QHash.addElement();
}

A
{
   QHash;
   B.takeThis(QHash);
   QHash.addElement();
}

To copy to clipboard, switch view to plain text mode 

Does the QHash get detached in this case? Or only when B modifies its own copy?

And if it does get detached, what happens when A modifies the QHash multiple times? Does it get detached every time?