Not if you have saved custom settings for other software like e.g. IBrowse.
Reset in main prefs will only reset global prefs.
The readme for 3.9 says you should delete the old prefs.
Just rename the MUI folder in ENV-ARC...
Well I did not and it worked anyway.
Now I encountered a problem in mui4 myself.
The PNG frames like that chip frames for example are invisible.
It works fine in Amikit but not in my custom workbench.
I used different datatypes(picture and png) removed all patches and even AfA and Scalos.
Not a chance.PNG frames stay invisible/transparent.
Does anyone have any idea what that could be?