Extra file selected after QFileSystemModel::setNameFilters()

Try select files for QTreeView like this:

QFileSystemModel* fsm = new QFileSystemModel(this);
fsm->setFilter(QDir::NoDotAndDotDot | QDir::AllDirs | QDir::Files );
fsm->setNameFilters( QStringList() << ".mp3" << ".flac" <<".ogg" << ".wav" << ".aac" << ".3gp" );

And make tree view as required.

You will get files with extension .m3u in the tree. Yes, they were not requested, And they won' be allowed for d-n-d operations.