Collapsing groups are not refreshed after tree swiching

Scenario:

1. Open "data/samples/CLUSTALW/COI.aln".
2. Build two trees for the alignment.
3. Set the vertical collapsing group delimiter somewhere in the tree view.
   Expected state: the rows names are colored.
4. Switch to another tree. Set the delimiter to another position.
   Expected state: the rows names are colored, groups are not the same as for the first tree.
5. Switch to the first tree.
   Expected state: the colors have been updated.
   Current state: the colors haven't been updated, they are incorrect for the current tree and its delimiter position.