Qt override.

        This is needed to be able to intercept the Tab key press event.

def event(self, event):
        """
        Qt override.

        This is needed to be able to intercept the Tab key press event.
        """
        if event.type() == QEvent.KeyPress:
            if (event.key() == Qt.Key_Tab or event.key() == Qt.Key_Space):
                text = self.text()
                cursor = self.cursorPosition()
                # fix to include in "undo/redo" history
                if cursor != 0 and text[cursor-1] == ' ':
                    text = text[:cursor-1] + ROW_SEPARATOR + ' ' +\
                        text[cursor:]
                else:
                    text = text[:cursor] + ' ' + text[cursor:]
                self.setCursorPosition(cursor)
                self.setText(text)
                self.setCursorPosition(cursor + 1)
                return False
        return QWidget.event(self, event)