Gajim doesn't properly cancel the first configuration form of a room.
Steps to reproduce the problem
Create a MUC Room, server sends status 201 and Gajim retrieves the configuration form, if I cancel the form Gajim silently dismiss it without cancelling with the server.
Whenever a room is in a locked state the room owner MUST configure the new room with either the defaults, mainly requesting an instant room, or with his data. In case the owner cancels the first configuration form, Gajim should send a form cancel to the server (see 10.1, example 162) or we might end with an indefinitely locked room.