An earlier process in Pharo which resulted in the appearance of a debugger window seems to be still running in the background and comes up again every time the image is started.
It seems to be have been triggered by an error in a startup process discussed in https://stackoverflow.com/a/78722508/172406.
These are the related windows
The Process Browser window.
Right clicking the items labelled (40)
and (40s)
brings up a menu with a Terminate
option and I suspect using it will prevent it from happening again.
It turns out that the image had been corrupted by a class which had some compiled in code in an error inducing state. In this state it wasn't an attempt to run an instance of object that was causing the problem. An attempt to scan the class information was leading to a state where a method call specific to the class was being propagated into the Morphic GUI which did not respond to it.
The problem was even more complicated as the class had already been deleted from the image
The solution was to insert a haltOnce
into class's code after adding a file whose absence caused the error.
All rather complicated but the long term solution is to start from a fresh image.