With fx115, changes from 49fe2b98d9
made the autocomplete popup appear blank when the reader tab is opened.
Not re-creating the PopupAutoComplete in tagsBox makes the items from
autocomplete popup visible again. But it makes the autocomplete appear
below the "Add tags" popup for annotations (what 49fe2b98d9
originally fixed), and it also creates a duplicate <popupset>
with a new autocomplete panel at the bottom of the DOM every time autocomplete runs.
The duplicate <panel>s do not have an id.
Manually adding a <popupset> with a <panel> whose id="PopupAutoComplete"
does not create any duplicates and properly positions the popup.
Fixes: #3881
89320a7ee4