#include <QtGui/qabstracttextdocumentlayout.h>
#ifndef QABSTRACTTEXTDOCUMENTLAYOUT_H
class QAbstractTextDocumentLayout: public QObject{
   /* Some contents are skipped to improve readability */
   protected: virtual void documentChanged(int from, int charsRemoved, int charsAdded) = 0;
   /* ... */
};
#endif // QABSTRACTTEXTDOCUMENTLAYOUT_H