textField = new QTextEdit;
  textField -> resize(500,600);
  fontBox = new QFontComboBox;
  
  connect(textField, SIGNAL(textChanged()), this, SLOT(modifyText())); 
  

...

void qOrganizer::modifyText()
{
 
   cursor = textField->textCursor();
   cursor.movePosition(QTextCursor::Left,QTextCursor::KeepAnchor);
   textField->setCurrentFont(fontBox->currentFont());
   cursor.movePosition(QTextCursor::Right);
};