so plug-ins cannot thaw what they haven't frozen, and the code
can clean up frozen stuff left behind by crashed or broken plug-ins.
Also redo the cleanup code so it only keeps track of the undo group
counts and freeze counts of what *this* GimpPlugInProcFrame did
itself. That should make it even stricter against broken code that
could mess up internals.
These procedures freeze/thaw the corresponding containers of the
image, allowing plug-ins that perform many changes affecting any of
these containers to suppress updates to the corresponding dialogs,
significantly improving performance.
which is just a #define to g_assert for now, but can now easily be
turned into something that does some nicer debugging using our new
stack trace infrastructure. This commit also reverts all constructed()
functions to use assert again.
It never belonged inside "tools". Also rename its "pdb" subdirectory
to "groups". This had to happen before 2.10 so cherry-picking between
branches doesn't become a nightmare in the future.