problem implementing proxy models in series

[Guett_31]

Here is what I’m trying to achieve:
I want to display sub parts of the File System in different windows from which I can select files.
I want that the selection automatically applies to all the files and all the sub-folders under the selection and I also want that each view displays the tree structure this way:
-Root_item(1)
-- item(1,1)
--- item(1,1,1)
--- item(1,1,2)
--- item(1,1,3)
-- item(1,2)
--- item(1,2,1)
--- item(1,2,2)
-- item(1,3)

In order to do those in an efficient way, I have decided to use proxy models so I can use only one instance of QFileSystemModel for all my views.
I use two proxy layers, one for the selection feature and anoter the "single root tree" display:
QFileSystemModel->ItemSelectionProxyModel->DisplayRootItemProxyModel->QTreeView. If I set my proxies that way everything works perfectly.

The problem occurs when I set my proxies like this:QFileSystemModel->DisplayRootItemProxyModel->ItemSelectionProxyModel->QTreeView. In that case the application fails to automatically select a few items (always the same ones) when I select a folder with a lot of files and subfolders.

I designed my two proxies from a IdentityFileSystemProxyModel base class, which is sub-classed from QIdentityProxyModel.
Here is code of the proxy base class, IdentityFileSystemProxyModel:

{
class IdentityFileSystemProxyModel : public QIdentityProxyModel
    Q_OBJECT
protected:
 
    QAbstractItemModel * m_model;
public:
 
    IdentityFileSystemProxyModel(QObject *parent = 0);
 
    void setSourceModel(QAbstractItemModel * sourceModel);
    virtual int columnCount(const QModelIndex & parent) const;
    virtual QString filePath(const QModelIndex & index) const;
 
signals:
    void directoryLoaded(QString path);
 
public slots:
    void directoryLoadedSlot(QString path);
};

{
class IdentityFileSystemProxyModel : public QIdentityProxyModel
    Q_OBJECT
protected:

    QAbstractItemModel * m_model;
public:

    IdentityFileSystemProxyModel(QObject *parent = 0);

    void setSourceModel(QAbstractItemModel * sourceModel);
    virtual int columnCount(const QModelIndex & parent) const;
    virtual QString filePath(const QModelIndex & index) const;

signals:
    void directoryLoaded(QString path);

public slots:
    void directoryLoadedSlot(QString path);
};

To copy to clipboard, switch view to plain text mode 

#include "IdentityFileSystemProxyModel.h"
 
IdentityFileSystemProxyModel::IdentityFileSystemProxyModel(QObject *parent) : QIdentityProxyModel(parent)
{
}
 
void IdentityFileSystemProxyModel::setSourceModel(QAbstractItemModel * sourceModel)
{
    m_model = sourceModel;
    QIdentityProxyModel::setSourceModel(m_model);
    QObject::connect(m_model,SIGNAL(directoryLoaded(QString)),this,SLOT(directoryLoadedSlot(QString)));
}
 
int IdentityFileSystemProxyModel::columnCount(const QModelIndex & parent) const
{
    return 1;
}
 
QString IdentityFileSystemProxyModel::filePath(const QModelIndex & index) const
{
    return data(index, Qt::UserRole + 1).toString();
}
 
void IdentityFileSystemProxyModel::directoryLoadedSlot(QString path)
{
    emit directoryLoaded(path);
}

#include "IdentityFileSystemProxyModel.h"

IdentityFileSystemProxyModel::IdentityFileSystemProxyModel(QObject *parent) : QIdentityProxyModel(parent)
{
}

void IdentityFileSystemProxyModel::setSourceModel(QAbstractItemModel * sourceModel)
{
    m_model = sourceModel;
    QIdentityProxyModel::setSourceModel(m_model);
    QObject::connect(m_model,SIGNAL(directoryLoaded(QString)),this,SLOT(directoryLoadedSlot(QString)));
}

int IdentityFileSystemProxyModel::columnCount(const QModelIndex & parent) const
{
    return 1;
}

QString IdentityFileSystemProxyModel::filePath(const QModelIndex & index) const
{
    return data(index, Qt::UserRole + 1).toString();
}

void IdentityFileSystemProxyModel::directoryLoadedSlot(QString path)
{
    emit directoryLoaded(path);
}

To copy to clipboard, switch view to plain text mode 

Here is how the QFileSystemModel , the two proxies and the view are connected for QFileSystemModel->DisplayRootItem->ItemSelectionProxyModel->QTreeView:

void FileSysSelectView::setRootIndex(const QModelIndex & index)
{
    //from sourceModel to rootItemModel
    QModelIndex proxIdx = m_rootModel->mapFromSource(index);
 
    m_rootModel->setHomeIndex(proxIdx);
    proxIdx = m_rootModel->getHomeIndex();
 
    //from rootItemModel to selectModel
    proxIdx = m_selectModel->mapFromSource(proxIdx);
 
    QTreeView::setRootIndex(proxIdx);
}
 
void FileSysSelectView::setModel(QAbstractItemModel * model)
{
    m_sourceModel = static_cast<QFileSystemModel *> (model);
    m_rootModel = new RootItemProxyModel();
    m_selectModel = new SelectItemProxyModel();
 
    m_rootModel->setSourceModel(m_sourceModel);
    m_selectModel->setSourceModel(m_rootModel);
 
    QTreeView::setModel(m_selectModel);
    QObject::connect(m_selectModel,
                     SIGNAL(dataChanged(QModelIndex, QModelIndex)),
                     this,
                     SLOT(ExpandItems(QModelIndex, QModelIndex)),
                     Qt::DirectConnection);
}

void FileSysSelectView::setRootIndex(const QModelIndex & index)
{
    //from sourceModel to rootItemModel
    QModelIndex proxIdx = m_rootModel->mapFromSource(index);

    m_rootModel->setHomeIndex(proxIdx);
    proxIdx = m_rootModel->getHomeIndex();

    //from rootItemModel to selectModel
    proxIdx = m_selectModel->mapFromSource(proxIdx);

    QTreeView::setRootIndex(proxIdx);
}

void FileSysSelectView::setModel(QAbstractItemModel * model)
{
    m_sourceModel = static_cast<QFileSystemModel *> (model);
    m_rootModel = new RootItemProxyModel();
    m_selectModel = new SelectItemProxyModel();

    m_rootModel->setSourceModel(m_sourceModel);
    m_selectModel->setSourceModel(m_rootModel);
    
    QTreeView::setModel(m_selectModel);
    QObject::connect(m_selectModel,
                     SIGNAL(dataChanged(QModelIndex, QModelIndex)),
                     this,
                     SLOT(ExpandItems(QModelIndex, QModelIndex)),
                     Qt::DirectConnection);
}

To copy to clipboard, switch view to plain text mode 

I think the problem comes from the IdentityFileSystemProxyModel base class:
If I do QFileSystemModel->ItemSelectionProxyModel->QTreeView , I have no selection problem.
If I do QFileSystemModel->IdentityFileSystemProxyModel->ItemSelectionProxyModel->QTreeView, I have the same selection problem I mentioned earlier.
I have been unsuccessful to figure out what was wrong so far...

Attached is a compilable project that shows the problem.

Thanks in advance!