[wp-trac] [WordPress Trac] #42126: Customize: Fix confusion related to visibility of Themes panel and drafted/scheduled changesets

[WordPress Trac]

#42126: Customize: Fix confusion related to visibility of Themes panel and
drafted/scheduled changesets
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 Reporter:  westonruter   |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  4.9
Component:  Customize     |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
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 With the addition of drafting and scheduling of changesets in #39896, we
 do not allow for theme switching to be done when a changeset has been
 saved as a draft or scheduled. There are a few technical reasons for this:

 * Changesets cannot be scheduled with a theme switch. This is because when
 a changeset post gets published during WP Cron, the new theme is not
 active and so none of the theme-specific settings will be loaded.
 * Publish settings section not available for theme preview because non-
 authoritative users cannot preview theme switch, so presenting the
 “preview link” control could result in users not being able to access it.
 * The previewed theme is not stored in the changeset, and so when
 returning to the Customizer later the theme being previewed at the time of
 saving would not then be restored. See #39031.

 There may be future ways around these issues, but for 4.9 the scope is to
 just disable theme switching when you have drafted or scheduled changes.

 However, there are currently two issues with the current implementation:

 1. As soon as you switch the status to draft or scheduled, the Themes
 panel disappears without warning. Users will not know where it went and
 why. There needs to be a notification explaining why they cannot switch
 themes. See conversation at
 https://wordpress.slack.com/archives/C0381N237/p1506983729000264
 2. If you have drafted or scheduled a changeset, if you go to the Themes
 admin screen and click Live Preview for a different theme, the Customizer
 is currently allowing the theme preview even though it has autoloaded the
 pending changeset. This results in the themes panel being hidden even
 though the button says "Activate & Publish". This is wrong, and when the
 Customizer is loaded with a non-active theme then we need to prevent
 establishing an existing changeset (and so a new changeset would be
 created as in branching mode). Reported here:
 https://wordpress.org/support/topic/unable-to-see-new-theme-browsing-
 experience-in-customizer/

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Ticket URL: <https://core.trac.wordpress.org/ticket/42126>
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