The flat inspector's Text FlatGroup rendered unconditionally, showing an
empty "Text" header for non-text elements (image, video, etc). Gate it on
isTextEditableSelection(element) so it disappears entirely when there's no
text to edit.
Also, the legacy multi-field TextSection (used as a fallback when an
element has 2+ text fields) rendered its own internal "Text" heading
nested inside the new flat Text FlatGroup, producing a doubled "Text"
heading. Add a hideOwnHeading prop to TextSection (default false, so its
other — legacy, non-flat — call site is unaffected) and pass it from
FlatTextSection's fallback path.
Vance Ingalls