Hi!
I do not have a solution, but Object>>initialExtent was recently deprecated and this causes great usability problem. This deprecation is very valuable for a clean UI separation. However, I have a warning deprecation each time a window is open. The reason stems from the method:
SystemWindow>>initialExtent ^ model initialExtent
For now, in my image, I suppressed this deprecation. Again, I do not have a clean solution.
Cheers, Alexandre