[wp-trac] [WordPress Trac] #65328: editor-expand.js DFW button remnant causes intermittent TinyMCE editor height miscalculation in WordPress 7.0

[WordPress Trac]

#65328: editor-expand.js DFW button remnant causes intermittent TinyMCE editor
height miscalculation in WordPress 7.0
--------------------------+-----------------------------
 Reporter:  MadtownLems   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  TinyMCE       |    Version:
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 Disclosure: This is an AI-assisted bug report. I've done my best to
 investigate its accuracy, but it's a bit out of my area of expertise. I
 used AI to help debug the problem that I noticed.


 In WordPress 7.0, the Distraction Free Writing (DFW) button no longer
 appears in the TinyMCE toolbar, indicating the feature was removed or
 disabled. However, wp-admin/js/editor-expand.js still contains code that
 registers the DFW button with TinyMCE and immediately hides it during the
 editor init event:

 editor.on( 'init', function() {
     if ( button.disabled() ) {
         button.hide();
     }
 } );

 This button.hide() call triggers a TinyMCE reflow/repaint cycle (via
 theme.js) at a moment when the new React-based admin UI introduced in 7.0
 has not finished laying out. The result is an incorrect height being
 stamped onto #mceu_31-body, causing the TinyMCE editor area to render with
 a large empty gray space.
 The bug is intermittent because it is a race condition between React
 finishing its layout and TinyMCE firing init. It reproduces most reliably
 on a hard refresh (Shift+F5).
 Steps to reproduce:

 Install WordPress 7.0
 Use the Classic Editor (either via the Classic Editor plugin or
 add_filter( 'use_block_editor_for_post', '__return_false' ))
 Open any post for editing
 Hard refresh (Shift+F5) repeatedly until the bug appears

 Expected result: TinyMCE editor renders at the correct height.
 Actual result: #mceu_31-body receives an inflated inline height (e.g.
 459.391px) while the inner #content_ifr iframe is a normal size, leaving a
 large gray gap.
 Root cause: The DFW button registration and hide logic in editor-expand.js
 was not removed when DFW support was dropped in 7.0. Removing that block
 should resolve the issue.
 Workaround: None confirmed beyond avoiding hard refreshes.

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Ticket URL: <https://core.trac.wordpress.org/ticket/65328>
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