breaks SOLID

It doesn't. In fact, if it worked as you expected it would break SOLID

it's definitely a serious design flaw

Sorry to be brutal: No, it's not a flaw, you just didn't understand the design of model/views.
To help you get a better idea of what is going on, try use the same model with 2 different treeviews. In only one of the view call setRootIndex, and then trigger the filtering.

Ok I found what was causing this awful bug.

When I check if the map contains the index, I actually check the raw index not the QPersistantModelIndex so this is not the same object and I think qmap does not check equality using == operator .

So I have to iterate over the map and check using QPersistantModelIndex "==" operators which can compare from a QModelIndex.

Hi,

Apply the same filter you are using for your single folder version except that this time rather than using a QString you should keep a QStringList of the folders you want to show and use that.

That wasn't really clear from your original description.

In that case, use a filter. QSortFilterProxyModel for example

Thanks a lot. :) @raven-worx @giupigna. Problem solved.

@tokafr
Super.
so it can copy files on its own ?
Doc hinted it, but I was not sure.

@tokafr
Oh. That would have been too easy then :)

http://stackoverflow.com/questions/11050977/removing-a-non-empty-folder-in-qt
has a function that looks good.
bool removeDir(const QString & dirName)
make sure to give it full path.

I dont think QFileSystemModel can do it directly .
Not that i have seen.

That I understood. That's why I think that QDirIterator is a better tool to find what you want on your drive.

Thanks everybody

You're welcome !

By the way, now you can use the "Topic Tool" button to mark the thread as solved, it keeps the things cleaner :)

Brilliant thanks!

@Chris-Kawa I am building from within Qt Creator (Windows 7), my .pro file didn't contain that! it just had:

QT += gui

Thank you Chris.