[wp-trac] [WordPress Trac] #54418: Admin menu sidebar: Customizer menu item is not visible when a classic theme is active

[WordPress Trac]

#54418: Admin menu sidebar: Customizer menu item is not visible when a classic
theme is active
----------------------------+---------------------
 Reporter:  poena           |       Owner:  (none)
     Type:  defect (bug)    |      Status:  new
 Priority:  high            |   Milestone:  5.9
Component:  Administration  |     Version:  trunk
 Severity:  normal          |  Resolution:
 Keywords:  has-patch       |     Focuses:  ui
----------------------------+---------------------
Changes (by hellofromTonya):

 * keywords:  needs-patch => has-patch


Comment:

 = Test Report

 Env:
 * WordPress: latest `trunk` at time of this report (5.9-alpha)
 * Plugins: none
 * Theme: switched between TT2, TT1, TT0, and Twenty Nineteen
 * OS: macOS Big Sur
 * Browser: Chrome, Firefox, Safari, and Edge

 == Steps

 Steps to reproduce:
 1. Pull the latest `trunk` version (or use Beta Tester plugin)
 2. Activate TT2. Notice the Customize menu does not display under
 "Appearance"
 3. Activate TT1. Customize menu should display under "Appearance", but it
 does not.
 4. Repeat with other bundled themes. Same result.

 After applying [attachment:"54418.diff"]:
 1. Activate TT2. Customize menu should not display.
 2. Activate TT1. Customize menu should display under "Appearance".
 3. Repeat with other bundled themes. Customize menu should display.

 == Results

 I can able to reproduce the reported issue. The Customize menu item does
 not display for any themes.

 When applying [attachment:"54418.diff"]:
 * With TT2, works as expected, i.e. Customize menu does not display ✅
 * With TT1, menu is restored as it was in 5.8 ✅
 * With Twenty Twenty, menu is restored ✅
 * With Twenty Nineteen, menu is restored ✅

 == Can a block template theme also show the Customize menu?

 Steps to Test:
 1. Activate TT2
 2. Add temporary testing code in the theme's `functions.php` file:
 {{{#!php
 /**
  * For testing purposes, add a callback to show the Customize
  * menu in position 7 in a block template theme.
  */
 add_action( 'customize_register', '__return_true' );
 }}}
 3. Refresh the browser. Notice the Customize menu item displayed below the
 "Editor" menu item.

 Results:
 Yes, a block template theme like TT2 can show the Customize menu when
 there's a callback registered to `'customize_register'`. Works as expected
 ✅

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Ticket URL: <https://core.trac.wordpress.org/ticket/54418#comment:9>
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