Solved Thunderbird windows border is missing

[Charlie Brown]

Hey,

The only thing that went wrong with the upgrade from plasma5 to plasma6 is that Thunderbird do not have the system windows setting anymore. Is it a bug ? Anyone experiencing the same thing with Thunderbird?

Thank you.

 

[Charlie Brown]

Just found the solution In settings => General, scrolled down to Window Layout and unchecked => Hide system window titlebar option.