Final "Rectangle" tree view is not the same as initial

Affected tests:

• GUITest_common_scenarios_options_panel_MSA_tree_settings_test_0003
• GUITest_common_scenarios_options_panel_MSA_tree_settings_test_0004

Scenario:

1. Open "COI.aln".
2. Open the tree settings option panel tab and build a tree.
3. Save an image for the default "Rectangle" tree view.
4. Select "Circular" tree layout.
5. Select "Rectangle" tree layout again and save an image.
   Expected state: the second image should be the same as the first one.
   Actual state: the images are different, distance between the lines has increased.