I think I've narrowed it down which explains the new behavior. In 5.7, the address bar was linked to all tools. In 6.0 this is not the case, and the bar will disregard any value that does not apply to the currently focused tool.

For example, type `pre_base' when the class tool has the focus. In 6.0, it will reset itself and when you click again it is empty. However, if you now switch to the diagram tool it gets targetted to `pre_base'.

Although confusing, this would require a lot of changes to get a behavior that would be possibly less confusing due to our various callbacks that can change the value of the address bar.

If you agree I would remove this one from the critical bug list.