Just use $(LANG=C /usr/bin/thunderbird) to make lightning works again.
This bug is reproducible on my daily Stretch.
- Bug#908494: lightning: no icon to access calendar... Carsten Schoenert
- Bug#908494: lightning: no icon to access calendar afte... George B.
- Bug#908494: lightning: no icon to access calendar... Carsten Schoenert
- Bug#908494: lightning: no icon to access calendar afte... George B.
- Bug#908494: lightning: Same problem for me Michael Domann
- Bug#908494: thunderbird: lightning vanished Steffen Müller
- Bug#908494: Related to thunderbird-l10n-de Steffen Müller
- Bug#908494: Related to thunderbird-l10n-de Pierre Dinh-van
- Bug#908494: Bug #908494 (lightning) Hartmut Krüger
- Bug#908494: Confirmed, reproducible on plain Stretch Daniel Lange
- Bug#908494: lightning: no icon to access calendar afte... Dio Putra
- Bug#908494: lightning: no icon to access calendar... Carsten Schoenert
- Bug#908494: lightning: no icon to access calendar afte... Tim Riemenschneider
- Bug#908494: lightning: no icon to access calendar... Carsten Schoenert
- Bug#908494: lightning: no icon to access cale... Tim Riemenschneider
