The Screen::show takes ownership of the screen pointer. I decided to
switch the parameter to std::unique_ptr to make the pointer ownership
explicit. The unique_ptr then provides automatic screen destruction in
Screen::show unless pointer is inserted or is already in the linked list
that is managed by df.
This requires plugins to pass plugin_self to Screen::show(), but
avoids the need to implement special checks in plugin_onstatechange
for the SC_BEGIN_UNLOAD event.
lethosor
Pauli
Ben Lubar
PeridexisErrant
Anuradha Dissanayake