code: def sizeHint(self, column):
          
          hint = super(XTreeWidgetItem, self).sizeHint(column)
          hint.setHeight(max(hint.height(), self.fixedHeight()))
          return hint
docs: Returns the size hint for this column.  This will return the width
          for the given column, with the maximum height assigned with this item.
          
          :return     <QtCore.QSize>