Bugzilla

The "multiple superimposed print dialogs" thing doesn't seem to be required, actually; I was just able to trigger this crash with two entirely separate print operations (i.e. my comment 26 STR, but without the "rapidly press ctrl+p" thing; just printing once with ctrl+p, completing that operation, and then printing again with ctrl+p).

I also was able to build libgtk locally, with debug info/symbols, and run Firefox with that locally-built library.  For whatever reason, my locally-built library doesn't trigger the crash -- but at the moment when I'd expect a crash, I do get a GTK nonfatal assertion-failure that seems to be a symptom of the same trouble:
```
Gtk-CRITICAL **: 11:41:26.372: gtk_printer_get_name: assertion 'GTK_IS_PRINTER (printer)' failed
```
That's probably a signal that we're passing a bogus object of some sort into `gtk_printer_get_name`, and for whatever reason it hasn't been poisoned yet, but it's still a landmine.

Here's a pernosco trace where we hit that gtk assertion failure:
https://pernos.co/debug/DUwm21zoKTPK5aRy37dSfg/index.html#f{m[A0G2,GcCZ_,t[KA,ENHV_,f{e[A0G2,GcCZ_,s{af6RSwAAA,bGw,uvBEL,ovHil___,v[{wiLg,v[{f'list',q'stdouterr',p{_,xAYag_,{f'container',q'stack',p{_,xAYag___,{w/eg,v[{f'source',q'source',p{_,xAYag_,{f'list',q'execution',p{'symbol''gtk_printer_get_name'_,xAYag____/

The "multiple superimposed print dialogs" thing doesn't seem to be required, actually; I was just able to trigger this crash with two entirely separate print operations (i.e. my comment 26 STR, but without the "rapidly press ctrl+p" thing; just printing once with ctrl+p, completing that operation, and then printing again with ctrl+p).

I also was able to build libgtk locally, with debug info/symbols, and run Firefox with that locally-built library.  For whatever reason, my locally-built library doesn't trigger the crash -- but at the moment when I'd expect a crash, I do get a GTK nonfatal assertion-failure that seems to be a symptom of the same trouble:
```
Gtk-CRITICAL **: 11:41:26.372: gtk_printer_get_name: assertion 'GTK_IS_PRINTER (printer)' failed
```
That's probably a signal that we're passing a bogus object of some sort into `gtk_printer_get_name`, and for whatever reason it hasn't been poisoned yet, but it's still a landmine.

Here's a pernosco trace where we hit that gtk assertion failure, with my local debug build of gtk (so hopefully fairly-debuggable), and with `GTK_DEBUG=printing` to add various bits of logging around gtk printing internals:
https://pernos.co/debug/DUwm21zoKTPK5aRy37dSfg/index.html#f{m[A0G2,GcCZ_,t[KA,ENHV_,f{e[A0G2,GcCZ_,s{af6RSwAAA,bGw,uvBEL,ovHil___,v[{wiLg,v[{f'list',q'stdouterr',p{_,xAYag_,{f'container',q'stack',p{_,xAYag___,{w/eg,v[{f'source',q'source',p{_,xAYag_,{f'list',q'execution',p{'symbol''gtk_printer_get_name'_,xAYag____/