Collapsing mode shared between an alignment and a tree

Scenario to reproduce:

1. Open "data/samples/CLUSTALW/COI.aln".
2. Build a tree for the alignment.
3. Collapse a group in the tree view.
   Expected state: the alignment is in the collapsing mode.
   Current state: the alignment is not in the collapsing mode.

Also, the tree view doesn't apply collapsing mode enabling/disabling from the Alignment Editor.