Was running this version: WindowBlinds 10.84 (059 - Windows 10 Edition) - 64 bit OS
Upgraded to the latest version as asked. Did look at the version. This is the download: (bottom)

Will not skin firefox 78.10.0esr (64-bit)

Worked great on on 10.84.
Uninstalled windowblinds and reloaded 10,84. and still can't skin firefox. Unset and reset firefox toolbar mode. still no good.
Windows version

Any ideas what has happened. Rollup/Down Multiple Firefox windows was my main reason for windowblinds.
Don't know if this is part of it. Was Playing around with groupy before this. It was ON when I upgraded Windowblinds.
Thanks
Mick