gtk builder and object id uniqueness

[Sebastian Kuzminsky]

Hello Glade people!

I'm from the LinuxCNC project (www.linuxcnc.org). We make
free/open-source CNC machine control software for milling machines,
lathes, 3d printers, robots, etc. We use Glade for some of our GUIs,
and we just ran in to a problem that I'd appreciate your input on.

One of our GUIs uses multiple .glade files and reads them into a single
gtk builder. This has worked well since the Ubuntu Hardy days. But
when we recently tried it on Ubuntu Precise and Debian Wheezy, we got
unexpected behavior - a GtkSpinButton suddenly started using the wrong
GtkAdjustment.

We believe the bad behavior comes from a bug in our code. One of our
glade files defines a GtkAdjustment with id 'adjustment1' and uses it in
a GtkSpinButton. Another glade file also defines a GtkAdjustment with
id 'adjustment1' and uses it in a different GtkSpinButton. This worked
in Hardy and Lucid, but in Precise and Wheezy one of the GtkSpinButtons
gets the wrong GtkAdjustment (ie, the adjustment from the other file).

GtkBuilder's add_from_file() doesn't complain, since no single file
contains object id collisions.

Is there some way to guard against id collisions across glade files?
Some of our glade files are managed by us, but we also have a couple of
GUIs that can load user-provided glade files... I tried wrapping
add_from_file() to walk the Buildable objects already in the builder and
compare their ids against the ids in the new glade file, but
GtkAdjustment isn't a Buildable and i couldn't figure out how to access
it's id.

What's the proper way to fix this id collision? Is there any notion of
a "local to this glade file" id namespace?

Should we simply change the id of every object in our glade files so
they have globally unique ids?

Should we change our code to use a different gtk builder for each glade
file?