connect(firstColHandle, SIGNAL(positionChanged(qreal)), this, SLOT(handlePositionChanged(qreal)));
connect(secondColHandle, SIGNAL(positionChanged(qreal)), this, SLOT(handlePositionChanged(qreal)));
connect(firstColHandle, SIGNAL(positionChanged(qreal)), this, SLOT(handlePositionChanged(qreal)));
connect(secondColHandle, SIGNAL(positionChanged(qreal)), this, SLOT(handlePositionChanged(qreal)));