Windows Thunderbird Message composer does not support Overwrite (only Insert mode)

[hlcRaleigh]

Numerous Windows text editors (e.g., NotePad, NotePad++, LibreOffice Writer) support Overwrite mode (new text replaces old text to the right on the cursor) in addition to Insert mode (adding text at the cursor). Some (LibreOffice Writer) do it elegantly by updating a status field. Others (NotePad++) change the cursor to reflect overwrite. A few (NotePad) silently support Overwrite mode with no status or cursor change. Thunderbird up to 152.0 (and a lot of other text entry objects) always is in Insert mode. This is a minor nuisance.