Qt: ProxyModel, QTreeView and Delegate Setup with filtering does not correctly update - expand

Question

I have a setup with QTreeView displaying a QSortFilteredProxyModel with custom filtering in filterAcceptsRow() accepting only rows depending on the value of a parent row value (selected in a QComboBox via QStyledItemDelegate-derived class. For example, if I choose in a row "Type" the value "BMW", I wanna display children for this special case.
This works great for the first item, I can choose these values inside of Item1 multiple levels down (up to 5 levels). Everything works great.
However, i've notice that once i am playing with item1 and this custom filtering and then adding an item2, the problems start. First thing I notice is, that QTreeView does un-expand the common parent of item1/item2 and displays only the children of the root item. The normal behaviour (and behaviour of adding item1 does like that) is expand the parent of item1. Why this gets confused on the second item and ONLY IF ive been playing with the item1 children-settings, idk.
Also, Ive noticed that in item2 the filtering does not work correctly. I have a QComboBox in item2->Type that have children depending on item2->Type value.. the first child for default value of the QComboBox still gets displayed like it should, but when changing QComboBox the view does not get updated any longer and stays with this first loaded child inside item2/item3/... However, the Delegate::setModelData gets called with the correct value/index and calls TreeItem->setData() accordingly. Its just that the filtering seems to be stuck with the old value of TreeItem->data(). Please note again, that this does only occur after ive been playing with item1.. If i leave that item untouched, I can correctly play with all other items (item2, item3, ...) and its doing fine.
I would be very happy if anybody can help.
Does anybody have tipps for me, what might cause the "reset" of expandedStates, even though the expand() gets called the same for item1 and item2 insertion and works great for item1 ?
What might cause my further problems?
ExampleDelegate.h
class ExampleDelegate :
public QStyledItemDelegate
{
Q_OBJECT
public:
ExampleDelegate(QObject* parent = 0);
~ExampleDelegate(void);
QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const;
void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const;
void setEditorData(QWidget* editor, const QModelIndex &index) const;
}
ProxyModel.h
class ProxyModel :
public QSortFilterProxyModel
{
Q_OBJECT
public:
ProxyModel(QObject *parent);
~ProxyModel(void);
void refresh();
void doReset();
pthread_mutex_t* proxyMutex;
int rowCount(QModelIndex& parent) const;
bool hasChildren ( const QModelIndex & parent = QModelIndex() ) const;
QModelIndex parent(const QModelIndex &index) const;
QModelIndex index(int row, int col, QModelIndex& parent) const;
bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const;
};
ProxyModel.cpp
bool ProxyModel::filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const {
printf("ProxyModel::filterAcceptRow \n");
pthread_mutex_lock(this->proxyMutex);
QAbstractItemModel* source = this->sourceModel();
QModelIndex index = source->index(sourceRow, 0, sourceParent);
TreeItem* item = ((TreeItem*) index.internalPointer());
if(item != NULL) {
int showOnly = item->showOnlyParentDetailDialog;
if(showOnly != -1) {
TreeItem* parent = ((TreeItem*) index.internalPointer())->parent();
if(parent != NULL) {
int parentOption = parent->selectedIndex;
//printf("parentOption: %u \n", parentOption);
bool result = (showOnly == parent->selectOptions->at(parentOption).detailDialog);
pthread_mutex_unlock(this->proxyMutex);
return result;
} else {
pthread_mutex_unlock(this->proxyMutex);
return true;
}
}
}
pthread_mutex_unlock(this->proxyMutex);
return true;
}