void CompletingTextEditPrivate::insertCompletion(const QString &completion)
{
    if (m_completer->widget() != m_backPointer)
        return;
    QTextCursor tc = m_backPointer->textCursor();
    int extra = completion.length() - m_completer->completionPrefix().length();
    tc.movePosition(QTextCursor::Left);
    tc.movePosition(QTextCursor::EndOfWord);
    tc.insertText(completion.right(extra));
    m_backPointer->setTextCursor(tc);
}