Site Editor: Snackbar notifications reappear which switching between view and edit mode

[glendaviesnz]

Description

The likes of 'Template reverted' snackbar notifications appear to be dismissed in the site editor view mode, but then reappear when going into edit mode.

We should dismiss all snackbars when moving between modes.

Step-by-step reproduction instructions

• Edit a template part
• Go to manage all template parts screen
• Revert the template changes
• Go back to the main Design browse page and notice that snackbar has gone
• Go into the site editor and notice the snackbar is back

Screenshots, screen recording, code snippet

snack-is-back.mp4

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[jameskoster]

We should dismiss all snackbars when moving between modes.

I don't know that this is necessarily the correct solution. If you move between modes quickly after performing an action then you'd lose the Snackbar, potentially before you had time to read it.

Looking at the video, the problem seems to be that the Snackbar is visually hidden when you move up a level in the drilldown, but is still present in the DOM and so re-appears if you enter edit view before it has timed out. It would be good to fix that for sure. My instinct is that there should only be 3 ways a Snackbar is dismissed:

1. The user clicks to close, or clicks the supplementary action if there is one (e.g. Undo).
2. It times out naturally.
3. A threshold is reached where it's not economical to display all the Snackbars at once (IE only display max 4-5, or something).

Possibly a separate issue, but it's also not ideal how the Snackbar is repositioned during the animation between modes. Preferably they exist on a layer above the rest of the UI, and are always fixed in position regardless of mode, kind of like dialogs.

[talldan]

I've noticed there's also a bug where the timeout for snackbars resets when navigating between different parts of the editor. It seems to happen as there are a few different implementations of snackbars across the site editor and each instance resets the countdown.

As James mentions, it might best to have one snackbar implementation at a higher level if it can be made to look good in all the different views.

[youknowriad]

I think we now have a consistent place for snackbars, so this is solved.