Crash on closing window in the "Tabbed documents" mode

On Windows:

1. Select "Tabbed documents" mode in the Application Settings.
2. Open a document
3. Click the cross button of the window to close it

UGENE crashes!

On Linux UGENE behaves differently. It freezes in some cases (see below the request from a user):

1. Switch to tabbed interface
2. Load Multiple alignment or Grid profile or Distance matrix
3. Try to close from the 'x' button on tab
4. Ugene freezes

So, after the fixture this should be tested at least on Windows and on Linux.