how to setRootPath(...) on a QSortFilterProxyModel of a QFileSystemModel

[ChrisW67]

QModelIndex sourceIndex = QFSMfilenameView->setRootPath(qsPath); // gives a model index on the original model
QModelIndex proxyIndex = filenameSortFilterModel->mapFromSource(sourceIndex);  // converts that to an index on the proxy
// do something with the view(s) using the proxy index
ui->filenameListView->setRootIndex(proxyIindex);

QModelIndex sourceIndex = QFSMfilenameView->setRootPath(qsPath); // gives a model index on the original model
QModelIndex proxyIndex = filenameSortFilterModel->mapFromSource(sourceIndex);  // converts that to an index on the proxy
// do something with the view(s) using the proxy index
ui->filenameListView->setRootIndex(proxyIindex);

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You need the index on the proxy because those are the indexes the view(s) you have attached to the proxy will see and use.