CKEditor 5 compatability

I updated the way the entire contents of the summary are selected for replacement. It was junky to begin with. The update still needs the placeholder test, otherwise it will add some extra <br> elements (but it won't delete the entire contents of the WYSIWYG).

The CKE4 version of the plugin includes translations for English, German, Russian, and Ukranian. The strings that need to be translated are "Add details" (the title of the button) and "Details" (the default content that gets placed in the summary).

What is your preferred behavior when the summary is empty? Would you like it insert "Details"? That looks like intended behavior in the CKE4 version of the plugin (line 89). At one point I got that functionality working and I could add it again if you prefer. However, I left it out because when I used the CKE4 plugin and removed the default text the summary stays empty.

I added a commit that switches to Drupal.t() for string translation. That should pull in any existing translations (since that's what the CKE4 version used), or at least allow it to be manually translated. I did verify that after the change I could find the string in the interface translation module.

I'm OK with leaving the summary empty after it loses focus, particularly since it maintains parity with the CKE4 version.

If the above is OK, is there anything left to do?

I don't think there's anything else.

The only question I had was whether the keyup event needed to be added. It was initially added in the final patch for Issue 3201638 → . I'm not seeing the behavior is supposedly fixes (cursor jumping to the beginning), but maybe I'm missing something (I used Firefox on Mac). So I suppose it's not still needed.

Merged this into the 2.x branch, and will roll an alpha release soon to get feedback from site owners on how this works for them in Drupal 10.

Automatically closed - issue fixed for 2 weeks with no activity.

Should this work in CKEditor 5 on Drupal 9.5 using version 2.1.x-dev? I am not seeing a toolbar button. No errors in the log or the browser.