Regression: show/hide chromatogram with black triangle on the Sanger read does not work

Scenario:

1. Open "_test\general_common_data\sanger\alignment.gb".
2. Select "SZYD_Cas9_5B71" read.
3. Click on the black triangle directed down and right before the read name.
   Expected result: the read sequence should be displayed without its chromatogram.
   Actual result: nothing happens.

Affected test:

• GUITest_common_scenarios_mca_editor_test_0010