The documents in the documents tree/list view can only be sorted by name, path or opening order. It would be useful to add an option that lets the users sort the documents manually, for example by dragging the items of the view. For now the only way to do it is to set 'sort by opening order' and to reopen all documents in the wished order.

Reproducible: Always

Steps to Reproduce:
1. open a few documents
2. try to drag an item in the view
3. miss manual sorting option in documents-settings
Actual Results:  
i have to workaround

Expected Results:  
i can sort the documents manually