How to properly clear and change layouts?

[Asperamanca]

(Qt 4.7.3)

I am using QGraphicsGridLayout to lay out several QGraphicsWidgets.

On occasion, I want to re-arrange the items, and remove or add some items to the layout. I found that the methods provided don't exactly make this a piece of cake:

-) No clear() ? Seriously?
-) removeAt, but only with an index? What is this index supposed to mean? I didn't find it anywhere else.
-) How can I reset a row's fixed height, once I have set it?
-) Will now-unused rows and columns be removed automagically? Or will they remain as artifacts, and possibly use up space?

Here is what I tried so far:

I have written my own clear():

@void CCvui_WidgetManager::clearLayout(QGraphicsLayout* pLayout)
{
if ( ! pLayout)
{
return;
}

for (int i = pLayout->count()-1; i >= 0; --i)
{
    pLayout->removeAt(i);
}

}@

I have pointers to all my widgets as members, so I can temporarily handle the fact they are no longer "owned" by the layout.

Then, I have two possible layouts I want to be able to switch between:

@void CCvui_WidgetManager::arrangeLayoutForAnalogAndBinary()
{
clearLayout(m_pComponentLayout);

// All items are visible in this layout variant
m_pComponentLayout->addItem(m_pAnalogLegend,0,0,
                            Qt::AlignTop | Qt::AlignHCenter);
m_pComponentLayout->addItem(m_pDateLabel,1,0,
                            Qt::AlignBottom | Qt::AlignHCenter);
m_pComponentLayout->addItem(m_pBinaryLegend,2,0,1,2);
m_pComponentLayout->addItem(m_pValueScale,0,1);
m_pComponentLayout->addItem(m_pAnalogCurveCanvas,0,2);
m_pComponentLayout->addItem(m_pTimeScale,1,2,1,1);
m_pComponentLayout->addItem(m_pBinaryCurveCanvas,2,2,1,1);

}

void CCvui_WidgetManager::arrangeLayoutForBinaryOnly()
{
clearLayout(m_pComponentLayout);

m_pComponentLayout->addItem(m_pBinaryLegend,0,0,1,2);
m_pComponentLayout->addItem(m_pBinaryCurveCanvas,0,2,1,1);
m_pComponentLayout->addItem(m_pTimeScale,1,2,1,1);
m_pComponentLayout->addItem(m_pDateLabel,1,0,
                            Qt::AlignBottom | Qt::AlignHCenter);
// The following items are invisible, and therefore not added
// to the layout:
m_pAnalogLegend->setParentItem(m_pSpareComponents);
m_pAnalogCurveCanvas->setParentItem(m_pSpareComponents);
m_pValueScale->setParentItem(m_pSpareComponents);
// Set a parent so they are deleted correctly.

}@

As you can see, I use the same layout, the same cells, and the same items, but I arrange them differently. In addition, in layout variant "binaryOnly", I have a few invisible items, which I must "park" in an invisible item in order to keep the ownership clear.

The only solution that looks promising I have found so far is to
-) Remove all items from the layout
-) delete the layout
-) re-create the layout
-) re-add the items to the layout
-) re-add the layout to its parent

Is there any simpler, reliable way to re-arrange my items within the layout?