Cannot set language by drag-and-drop
Versions: Calibre 2.3 on windows 7
Steps to reproduce:
Search for "languages:false" to list the books with no languages specified.
Select several of them.
Drag-and-drop the selected books unto one of the languages listed under the "languages" category.
Edit the metadata for one of those books and notice the language field.
The language field is still empty.
The language field contains the name of the language targeted in the drag-and-drop action.