That's intentional. If the VM is not running, reverting (or creating) is so fast that the transition of the GtkStack we use to show the activity message (and the spinner) starts and then gets cancelled immediately which makes it looks like a weird graphical glitch.

I agree however that it's suboptimal to have activity indication in one case and not in another but fixing that probably requires another way of indicating the activity (spinner + message) and I'm not sure what the best method of doing so would be.

Given that we can make this consistent somehow for all cases: How about an animation to visualize that the current state now derives from another snapshot?

(In reply to comment #1)
> That's intentional. If the VM is not running, reverting (or creating) is so
> fast that the transition of the GtkStack we use to show the activity message
> (and the spinner) starts and then gets cancelled immediately which makes it
> looks like a weird graphical glitch.
> 
> I agree however that it's suboptimal to have activity indication in one case
> and not in another but fixing that probably requires another way of indicating
> the activity (spinner + message) and I'm not sure what the best method of doing
> so would be.

I'm actually not at all sure its justified to use stack here. Why not just a message (with spinner next to it) either above/under the snapshots, or maybe between the snapshot's name and the settings menu button?

(In reply to comment #2)
> Given that we can make this consistent somehow for all cases: How about an
> animation to visualize that the current state now derives from another
> snapshot?

What?

(In reply to comment #3)
> (In reply to comment #1)
> > That's intentional. If the VM is not running, reverting (or creating) is so
> > fast that the transition of the GtkStack we use to show the activity message
> > (and the spinner) starts and then gets cancelled immediately which makes it
> > looks like a weird graphical glitch.
> > 
> > I agree however that it's suboptimal to have activity indication in one case
> > and not in another but fixing that probably requires another way of indicating
> > the activity (spinner + message) and I'm not sure what the best method of doing
> > so would be.
> 
> I'm actually not at all sure its justified to use stack here. Why not just a
> message (with spinner next to it) either above/under the snapshots, or maybe
> between the snapshot's name and the settings menu button?

Oh, I just like the current version more visually (in case it works...), hiding/showing something above/below the list would have the downside of changing the scrollbar length (or even worse: causing the scrollbar to show). Adding a third page to the GtkStack in a SnapshotListRow would probably also be good but the current solution is also used when creating new snapshots.

(In reply to comment #4)
> (In reply to comment #3)
> > (In reply to comment #1)
> > > That's intentional. If the VM is not running, reverting (or creating) is so
> > > fast that the transition of the GtkStack we use to show the activity message
> > > (and the spinner) starts and then gets cancelled immediately which makes it
> > > looks like a weird graphical glitch.
> > > 
> > > I agree however that it's suboptimal to have activity indication in one case
> > > and not in another but fixing that probably requires another way of indicating
> > > the activity (spinner + message) and I'm not sure what the best method of doing
> > > so would be.
> > 
> > I'm actually not at all sure its justified to use stack here. Why not just a
> > message (with spinner next to it) either above/under the snapshots, or maybe
> > between the snapshot's name and the settings menu button?
> 
> Oh, I just like the current version more visually (in case it works...),
> hiding/showing something above/below the list would have the downside of
> changing the scrollbar length (or even worse: causing the scrollbar to show).
> Adding a third page to the GtkStack in a SnapshotListRow would probably also be
> good but the current solution is also used when creating new snapshots.

Hm.. how about a tiny artificial delay when reverting is too fast?

commit: ced5374 ced5374be02d169a6867952d4e332a2b61073924

    snapshots-list-row: Always display msg when reverting
    
    We were not displaying "Reverting to SNAPSHOT_NAME" message and spinner
    if machine was not in running state. The rationale was that in
    non-running state, reverting is a very quick operation and therefore the
    stack page switch animation looked weird.
    
    However reverting is not always very fast in this case and the missing
    indication is a bit of a UX failure when that happens. Moreover, the
    quick page switch doesn't look that weird after all. If we decide to
    still address the latter, we can always introduce a very short artificial
    delay.