Content Edit page jumps when media library item is placed.

Great find!

I have modified the patch so that it can be applied using composer. Had a similar issue in one of the projects and this worked fine for us. Not sure if this is the right way to solve this issue.

I can't get that patch to apply after updating to 8.8. Here's my patch. Not doing anything different.

Well, my patch failed testing. But I don't know enough about the Media Library code to make an educated guess about that assertion - whether I've broken something needed or the assertion needs altered.

    $open_button = $this->assertElementExistsAfterWait('css', '.js-media-library-open-button[name^="field_twin_media"]');
    $this->assertTrue($open_button->hasAttribute('data-disabled-focus'));
    $this->assertTrue($open_button->hasAttribute('disabled'));

Everything seems to work though.

Also posted this in #3089745: Add focus behaviour for media widget with max elements, not sure which issue to close as a duplicate, both issues have valuable patches. Anyway, my prefered solution would be to conditionally add the data-disabled-focus attribute.

In MediaLibraryWidget we have this:

    // When the user returns from the modal to the widget, we want to shift the
    // focus back to the open button. If the user is not allowed to add more
    // items, the button needs to be disabled. Since we can't shift the focus to
    // disabled elements, the focus is set back to the open button via
    // JavaScript by adding the 'data-disabled-focus' attribute.
    // @see Drupal.behaviors.MediaLibraryWidgetDisableButton
    if (!$cardinality_unlimited && $remaining === 0) {
      $element['open_button']['#attributes']['data-disabled-focus'] = 'true';
      $element['open_button']['#attributes']['class'][] = 'visually-hidden';
    }

We might want to check $form_state->getTriggeringElement() before we add the data-disabled-focus attribute. We only want to trigger the refocus when a user selected something in the library. The triggering element should be the media_library_update_widget button.

I think this might be the best way to fix this.

I am working on this.

I added new patch according comment #8, Kindly review.

#10 The changes to the JavaScript files are redundant: the 'Add media' button should only be focused programmatically when returning from the media library modal, but the button should also be visually-hidden when no more items can be added.

This raised notices because triggering element can be NULL.

Tried to debug the test fail, but the test fails much sooner locally then it does on the bot with what seem like unrelated fails ¯\_(ツ)_/¯

Now neither patch #13 nor #16 apply with Drupal 8.9.3

Looks like this was fixed in https://www.drupal.org/project/drupal/issues/3089745. Based on my manual testing, this is fixed.

I'm closing this issue as a duplicate.

Great! Really Great!!