[Bug]: Sigil AppImage Can't Detect Dark Theme on Fedora Workstation 42

Bug Description

It appears that the Sigil (and PageEdit for that matter) AppImages cannot detect the Dark Theme on Gnome for Fedora Workstation 42.

It also appears there is no way to manually select light or dark theme in the software.

Platform (OS)

Linux

OS Version / Specifics

Gnome 48, Fedora Workstation 42

What version of Sigil are you using?

current

Any backtraces or crash reports