Sorry about that. I’ve checked in a fix. Will be in 1.8.1.
You have to call window.removeDisplayRegion(rocketRegion) to remove Panda’s internal reference to your region, allowing it to be destructed when you clear up your references.
Note that calling “del variable” is functionally little different than doing “variable = None”. “del” doesn’t actually destroy the object like “delete” does in C++; it simply removes the reference to the object.