QFileSystemModel does not update when the contents of a file changes (file size)

When I create new files, QFileSystemModel picks up the changes (touch NewFile). However if I change the contents of a file, the view does not get updated (echo "foobar" > NewFile).

The QFileSystemWatcher does not emit the directoryChanged signal when a file has been modified. The documentation reads: "This signal is emitted when the directory at a specified path, is modified (e.g., when a file is added, modified or deleted) or removed from disk."

Test case main.cpp to reproduce issue

#include <QtGui> 
 
class TreeView : public QTreeView 
{ 
   Q_OBJECT 
public: 
   TreeView(QWidget *parent = NULL) : QTreeView(parent) { 
       QFileSystemModel *model = new QFileSystemModel(this);; 
       model->setRootPath("/"); 
       setModel(model); 
       setRootIndex(model->index(QDir::currentPath())); 
   } 
}; 
 
#include "main.moc" 
 
int main(int argc, char **argv) 
{ 
    QApplication a(argc, argv); 
    TreeView w; 
    w.show(); 
    return a.exec(); 
}