A simple overview selection rect is not updated on alignment changing

Scenario to reproduce:

1. Open "_common_data/clustal/test_1393.aln".
2. Show simple overview.
3. Select whole alignment.
   Expected state: whole simple overview is filled with a selection rect.
4. Click "Align sequence to this alignment" button on the tool bar and select "data/samples/fastq/eas.fastq".
   Expected state: sequences are added, two of five sequences are selected both in the sequence area and simple overview.
   Current state: sequences are added, two of five sequences are selected in the sequence area, but the simple overview if filled with a selection rect like whole alignment is selected.