void SCgCommandChangePairBeginEndDots::undo()
{
    SCgBaseCommand::undo();
    ChangeDotsInfo::const_iterator it = mChangeDotsInfo.constBegin();
    for(;it != mChangeDotsInfo.constEnd(); ++it)
    {
        SCgPair* pair = it.key();
        const QPair<BeginEndPairDots, BeginEndPairDots>& dotPositions = it.value();
        pair->setBeginDotPosition(dotPositions.first.first);
        pair->setEndDotPosition(dotPositions.first.second);
    }
}