Tree Window List doesn't work when i load kvirc.

[hyuma78]

I'm experiencing a strange issue. I'm using KVIrc 5.0.0 'Aria' 20160102 - build 2020-03-24 14:05:19 UTC - Linux (5.4.0-37-generic) on lubuntu 20.04LTS. When I launch Kvirc I can't see on the left the
Windows Tree List with the list of servers and channel where I'm in. On the menu settings there is the check on the "Show Tree Windows List". That's annoying because everytime I launch the client I've to press CTRL+T to see the menu on the left... any help? thanks