2017065 - Undo history lost in <textarea> after toggling display: none → display: block

Status: NEW

(Core :: DOM: Editor, defect)

Description

[silverwind]

Attachment: testcase.html

Steps to Reproduce:

1. Open the attached testcase (or save the HTML below to a file and open it in Firefox).
2. Type text into the <textarea>.
3. Make additional edits so undo history exists.
4. Click the "Hide" button (applies display: none).
5. Click the "Show" button (restores display: block).
6. Press Ctrl+Z (Cmd+Z on macOS).

Actual Results:

Undo does nothing. The previous edit history is lost after the element is hidden and shown again.

Expected Results:

Undo history should be preserved when toggling visibility via CSS (display: none -> display: block), since:

• The DOM node is not removed from the document.
• The value property remains intact.
• Other browsers (Chromium-based) preserve undo history in the same scenario.

Comment 1

[silverwind]

Note: There are a number of closed bugs about this issue, but I believe it's still in need of a fix, given that the same works fine in Chrome, so it's a webcompat issue. Some of them:

• https://bugzilla.mozilla.org/show_bug.cgi?id=58616
• https://bugzilla.mozilla.org/show_bug.cgi?id=1523270