[Qt-interest] Reordering items from QFileSystemModel presented in QTreeView

[Strahinja Markovic]

Hi all,

So I have a QFileSystemModel and a QTreeView. The tree view presents the 
items from the model as a nice file system hierrachy. I'd like the user to 
be able to reorder the way the files are displayed. 

For instance, let's say the tree looks like this:

folder
  file1
  file2
  file3

I want the user to be able to click on file1 and drag it between file2 and 
file3, so the view looks like this.

folder
  file2
  file1
  file3

Naturally, the files and the folder would be unchanged on disk. It's just 
the display that would change.

Currently, no matter what I try, when you try to drag-and-drop a file within 
its own folder, there's no change in the order of the items.

I've turned off sorting everywhere. On the tree view, I have:

tree->setSortingEnabled( false );
tree->sortByColumn( -1 );

and drag is enabled along with AcceptDrops and DropIndicatorShown. I've also 
created a subclass of QFileSystemModel and overridden the sort() method with 
an empty implementation. Nothing I try seems to work. 

I've looked at the "Using Drag and Drop with Item Views" page and done 
what's required, and I *know* I can make this work for say a subclass of 
QStandardItemModel. But I really don't want to roll my own version of a file 
system model when one already exists. 

I'd love to hear any suggestions regarding this matter. 

Sincerely,

Strahinja Markovic