Improvement: When updating all in stack view - last queue item shifts to the ungrouped stack

[begunfx]

When we try to update a full stack of containers using the "Update All" in stack view I noticed a peculiar behavior. When the last container in the stack to update starts updating it and the group that I triggered to update disappear with the final updating container reappearing in the ungrouped stack. From a UX perspective when a full stack/group is triggered to update only after the last container has completed the update, then the stack/group should disappear so the container update process is more consistent.

[s-b-e-n-s-o-n]

Thanks for the detailed report, @begunfx — and good catch.

You're right that a stack should stay intact for the whole update rather than dissolving the moment its last container starts. Here's what was happening: when a container updates, Drydock briefly removes the old container before the recreated one appears. For the last container in a stack, that left the stack with only a single live member for a split second — which tripped the rule that flattens genuine single-container stacks into the Ungrouped section (the behaviour you requested in #179). So the stack header vanished and the remaining container jumped to Ungrouped.

The fix makes the flatten decision key off how many containers are assigned to a stack, not how many happen to be live at that instant. A multi-container stack now stays grouped throughout the entire "Update All" run, even while its last container is mid-recreate. Genuine single-container stacks still flatten as before.

This will land in the next v1.5 release candidate.