[Oberon] ETH Oberon/Gadgets: System Freeze in unloading

[Patrick, Dr. med. Hunziker]

>>Gadgets.Insert BasicGadgets.NewButton
>>to Insert a button somewhere.
>>Then I execute
>>System.Free BasicGadgets~
>> makes the system freeze...

>Felix wrote: 
>Don't be so cruel to the poor Button. You have stolen its Handler. ;-) 
>Seriously: The Problem is: When freeing a Module, Oberon checks if there 
>are still other Modules depending on that module but it cannot check if 
>Objects are still using any Allocated Memory in that Module. In that 
>special case the allocated Memory was the Handler and moreover any 
>type-checks and type-casts could't work since the Module did not exist any 
>more (after successful freeing it) etc.

>So the "solution" is: Do not System.Free a Module when its Objects are 
>still displayed, since they are not deallocated and the Handler is called 
>any time a Display.Broadcast (or update message) is sent (which is the case 
>when new Viewers like a Trap-View are opened.)

>Felix.

Thanks for the info.
I see the problem.
However, in several years of working with Oberon, I have only found three ways to produce C-like system freezes
apart from using the unsafe SYSTEM feature:
A) calling C programs from within Oberon
B) passing very large arrays as value parameters in procedure headings
C) unloading modules whereby some visual gadget is still hanging around somewhere, as mentioned above.  
I feel system stability is a prominent one of the many highlights of Oberon, so the points B and C hurt the more...
Greetings
Patrick