Right
thanks a lot for the replies 
Yeah I got a bit confused and fed up with my work so far but I'm back on the road again.
and now I got a piece of code like this:
model
->setHeaderData
(0, Qt
::Horizontal,
QObject::tr("BLA1"));
model
->setHeaderData
(1, Qt
::Horizontal,
QObject::tr("BLA2"));
model->appendRow(parentItem);
parentItem->appendRow(subItem1);
model = new QStandardItemModel(0,2,this);
model->setHeaderData(0, Qt::Horizontal, QObject::tr("BLA1"));
model->setHeaderData(1, Qt::Horizontal, QObject::tr("BLA2"));
QStandardItem *parentItem = new QStandardItem("parent");
model->appendRow(parentItem);
QStandardItem *subItem1 = new QStandardItem("item1");
parentItem->appendRow(subItem1);
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and now I want a checkbox in the second row and second column i.e. next to subitem1, same row, next column, so I do:
model->setData(model->index(1, 1), Qt::Checked, Qt::CheckStateRole);
model->setData(model->index(1, 1), Qt::Checked, Qt::CheckStateRole);
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and thiiiis does nooooot work! tell me why tell me why
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