Lou Gogan via tde-users wrote on 9/14/23 14:30:
All I can advise is that AFTER closing the sidebar, MANUALLY save the session (sessions, save) close Kate, then open it again. The sidebar should remain closed.
At the "Sessions | Save" point, after closing the sidebar, I am prompted for a session name, which suggests that I will no longer have just one session.
But I gave it a name anyway. Then I closed kate. Then opened kate again. And the sidebar was still present.
Doc