Looks like a new bug introduced somewhere between build 95 and 116 (which I'm using):
I copied an action with two children, and now if I click on one of the child clones, the next sibling is in fact selected. Ie:
A
- B
-C
A+
-B+
-C+
D
When I click on B+, D gets selected. And in fact lots of really bizzare stuff where actions get repainted by different actions. And the tool tips for every action from A+ onwards (including E, F...) are blank but flash repeatedly. And in fact when I click on various different actions, it looks like several actions are selected simultaneously...but then they repaitn themselves without selection. All in all, a total mess.
Fortunately, after saving and reloading, the mess went away.
Steve