Multiple inheritance & Qt

[dublet]

This post is because of QQ15.

I have an existing application which has several object, all related, but not yet using a single unifying object to command a universal interface across these objects. There are 4 different main types, one table object (which inherits QTable), one graph object (which inherits QWidget) and two text objects (which both inherit QTextView).
All these object thusly have a common ancestor, namely QWidget.
Using single inheritance would be a solution, but would require the reimplementing of Qt code, which would make it harder to maintain and which should be needless in the first place.

As far as I can read from the article, the solution is to create an interface and a wrapper, as follows:

class Interface {
        public:
                virtual void method() = 0;
};
 
class Wrapper : public QWidget, public Interface {
        Q_OBJECT
                Interface *wrapped;
        public:
                Wrapper(QWidget *p) : QWidget(p) {
                        wrapped = cast_stuff<Interface *>(p);
                }
                ~Wrapper();
        public slots:
                void method() { wrapped->method(); }
};

class Interface {
        public:
                virtual void method() = 0;
};

class Wrapper : public QWidget, public Interface {
        Q_OBJECT
                Interface *wrapped;
        public:
                Wrapper(QWidget *p) : QWidget(p) {
                        wrapped = cast_stuff<Interface *>(p);
                }
                ~Wrapper();
        public slots:
                void method() { wrapped->method(); }
};

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Then you create an object structure based on the interface:

class Document : public QWidget, public Interface {
        Q_OBJECT // Is this even necessary?
                Wrapper *wrapper;
        public:
                Document(QWidget *p = 0) : QWidget(p) { }
                virtual ~Document() { }
                virtual void method() { generic_implementation; }
};
 
class Table : public QTable, public Document {
        public:
                Table(QWidget *p = 0) : QTable(p), Document(0) {
                }
                ~Table() {
                }
                virtual void method() { specific_implementation; }
};

class Document : public QWidget, public Interface {
        Q_OBJECT // Is this even necessary?
                Wrapper *wrapper;
        public:
                Document(QWidget *p = 0) : QWidget(p) { }
                virtual ~Document() { }
                virtual void method() { generic_implementation; }
};

class Table : public QTable, public Document {
        public:
                Table(QWidget *p = 0) : QTable(p), Document(0) {
                }
                ~Table() {
                }
                virtual void method() { specific_implementation; }
};

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This is completely based on the example declarations. Now I have a few questions.
First of all, how would you go about creating a specific object?
Is it like this:

Interface *d = new Table();

Interface *d = new Table();

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(But then you wouldn't need the wrapper?)
Or would you use the wrapper, like so:

Wrapper *w = new Wrapper(new Table());

Wrapper *w = new Wrapper(new Table());

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Second, why would you include the Wrapper object in the Document, does the wrapped object need to know if it's being wrapped and if so, why?

I hope someone can help me with the problem, as Voker's example code didn't include any usage tips.