Two options panel tabs can be opened simultaneously by building trees in the Alignment Editor

Scenario:

1. Open "data/samples/CLUSTALW/COI.aln".
2. Open the "Tree Settings" options panel tab.
3. Build a phylogenetic tree.
4. Close the tree.
5. Open the "Pairwise Alignment" options panel tab.
6. Build a phylogenetic tree (use a toolbar button or "Actions" menu).
   Expected state: the "Tree Settings" tab is opened. There are no more opened tabs.
   Current state: both the "Tree Settings" and the "Pairwise alignment" tabs are opened simultaneously.