Yes, thats what I am doing right now;
Qt Code: 
  1. #include "customtreeview.h"
  2.  
  3. customtreeview::customtreeview(QWidget * parent)
  4. {
  5. }
  6.  
  7. void customtreeview::mousePressEvent(QMouseEvent *event)
  8. {
  9.     if (event->button() == Qt::LeftButton)
  10.     {
  11.         QDrag Drag( this );
  12.         QFileSystemModel *tempmodel = qobject_cast<QFileSystemModel *>(model());
  13.         QModelIndex tempindex = indexAt(event->pos());
  14.  
  15.         QPixmap tempmap(1,1);
  16.         QMimeData *mimeData = new QMimeData;
  17.         QList<QUrl>urllist;
  18.         QString filename=tempmodel->filePath(tempindex);
  19.  
  20.         emit setpreview(filename);
  21.  
  22.         urllist.append(QString("file:"+filename));
  23.         mimeData->setUrls(urllist);
  24.         tempmap.fill(Qt::white);
  25.         Drag.setPixmap(tempmap);
  26.         Drag.setMimeData(mimeData);
  27.         Drag.exec( Qt::IgnoreAction );
  28.      }
  29.      QTreeView::mousePressEvent(event);
  30. }
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I left everything else untouched.

I still struggle to understand how to set drag and drop behaviour correctly.