Vertical scrollbar for a short sequence in the Details View

Affected tests:

• GUITest_common_scenarios_sequence_view_test_0067

Scenario:

1. Open a very short sequence <50 (e.g. "_common_data/fasta/fa1.fa").
2. Click the "Show details view" button on the toolbar.
3. Click the "Wrap sequence" button on the left toolbar.
   Bug state: the Details View can be scrolled a bit (see the screenshot).