QTextDocument copy constructor

I'm writing a simple note-taking app.
On the left is a QTreeWidget to select a note; on the right is a QTextEdit to edit it.
Items in the QTreeWidget are TreeWidgetItem's :

class TreeWidgetItem: public QTextDocument, public QTreeWidgetItem

Everything works fine but now I want to copy/paste notes.

My problem concerns cloning a TreeWidgetItem.
I wanted to write a copy constructor:

TreeWidgetItem(const TreeWidgetItem &other) : TreeWidgetItem(other), QTreeWidgetItem(other){...}

but QTextDocument does not have a public copy constructor so I thought I'd write a clone method to use QTextDocument::clone() instead:

TreeWidgetItem *TreeWidgetItem::clone ( ){
TreeWidgetItem *clone = (TreeWidgetItem *)this->QTextDocument::clone(); //note nasty cast :eek:
...fix up TreeWidget stuff ...
return clone;
}

but then the QTreeWidgetItem default constructor would never get called.

I could get round the problem by having a QTextDocument as a field in TreeWidgetItem rather than inheriting directly but that would involve a lot of re-writing.

Does anyone have an elegant solution please?.

Bob.