Disbling JavaScript in Thunderbird:
Edit --> Preferences --> Advanced --> General,
search for 'java', set 'javascript.enabled' to 'false'.
Settings -> Scrolling -> Always show scrollbars
And:
Settings -> Config editor -> search: widget.gtk.overlay-scrollbars.enabled -> False
With the FilePicker opened in Thunderbird, right-click on the panel with files and you'll have the option to show hidden files.
A signature file requires the full path.
E.G.:
/home/joe/.signature
More;
Thunderbird
about:config Modifications
Not all settings are available in 'about:config' or 'config editor'. For
some things, you need to edit 'prefs.js';
Modify
Thunderbird settings
A list unsubscribe plugin.