Structs as C-subtype?

[fracek]

At the moment we declare structs with C-struct, the problem is that they are declared sealed. To make make work I had to change the declaration of <GTypeInstance> to define open C-subtype <GTypeInstance> (<C-void*>) (because make and gtypeinstance are in 2 different modules), do you think we could change the definition of every struct to this? Or can I work around the problem in a different way?