Wow, well spotted! Took me a while to notice that one, but there is an extra transition displayed that isn't necessary.

(In reply to comment #0)
> Closing an app that is not a favorite shrinks the dash. In previous versions
> this happens right away but in 3.6 the shrink animation only starts when you
> enter overview.

Not that it matters much, but this was always the case in previous versions. You may not have noticed it before, because the animations does not only start when entering the overview - the dash is updated while the overview is hidden, but work is done lazily (if you wait ~20 seconds after closing/opening an app, you should not see any resizing going on when entering the overview).

Anyway, patch coming ...

Created attachment 227679 [details] [review]
dash: Disable animations during overview transitions

When updating the dash, we already avoid all animations while the
overview is hidden. However, as we are using Main.queueDeferredWork(),
updates may be deferred up to ~20 seconds while the overview is hidden.
If the overview is entered before a queued update has taken place, it
will be run immediately on map - as the overview is visible by then,
this means animating any outstanding changes.
Work around this by skipping animations during overview transitions as
well.

I think I haven't noticed it in previous versions because the dash wasn't centered vertically. It's a lot more noticeable when the whole dash suddenly shrinks and moves, but you are correct - I noticed it on 3.4 now :)

Review of attachment 227679 [details] [review]:

Makes sense, the comments in the code need to be updated though (see below).
Fine to push with them fixed.

::: js/ui/dash.js
@@ +746,3 @@
             let item = removedActors[i]._delegate;
 
             // Don't animate item removal when the overview is hidden

The comments do not match the code anymore. Update them.

Attachment 227679 [details] pushed as f602993 - dash: Disable animations during overview transitions