It appears this is actually because glib2.0 is not compiled with --enable-debug so I'm reassigning this to glib2.0 and lowering the importance to wishlist as a new "feature".
I'm also attaching an ancient Debian bug asking for this compile option. Someone that cares about this feature should look into what the impact is of --enable-debug and have a conversation with the Debian maintainers about it. ** Package changed: gtk+3.0 (Ubuntu) => ubuntu ** Changed in: ubuntu Importance: Low => Wishlist ** Package changed: ubuntu => glib2.0 (Ubuntu) ** Bug watch added: Debian Bug tracker #170726 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=170726 ** Also affects: glib2.0 (Debian) via http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=170726 Importance: Unknown Status: Unknown -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to gtk+3.0 in Ubuntu. https://bugs.launchpad.net/bugs/1623763 Title: GTK Inspector Statistics tab non-functional Status in GTK+: Confirmed Status in Ubuntu GNOME: New Status in glib2.0 package in Ubuntu: Triaged Status in glib2.0 package in Debian: Unknown Bug description: Running a GTK+ 3 app with GOBJECT_DEBUG=instance-count enables the Statistics tab in GTK Inspector, but after clicking the Record button it never starts collecting statistics. This makes it difficult to develop and debug memory leaks in GTK programs on Ubuntu. To reproduce: 1. Start an app with the Inspector and GOBJECT_DEBUG=instance-count set, e.g.: > GOBJECT_DEBUG=instance-count GTK_DEBUG=interactive gnome-calculator 2. Click the Statistics tab 3. Click the Record button 4. Click around the app a bit Expected: Object counts go up, pretty graphs showing things Actual: Object counts stay at 0, pretty graphs showing flat lines This seems like it is Ubuntu-specific, since when running GTK+ programs installed via Flatpak (and hence using the Flatpak runtime), the above works fine on the same system. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: libgtk-3-dev 3.20.8-1ubuntu0~ppa1 [origin: LP-PPA-gnome3-team-gnome3-staging] ProcVersionSignature: Ubuntu 4.4.0-36.55-generic 4.4.16 Uname: Linux 4.4.0-36-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.1 Architecture: amd64 CurrentDesktop: GNOME Date: Thu Sep 15 13:05:19 2016 InstallationDate: Installed on 2015-07-22 (421 days ago) InstallationMedia: Ubuntu-GNOME 15.04 "Vivid Vervet" - Release amd64 (20150422) SourcePackage: gtk+3.0 UpgradeStatus: Upgraded to xenial on 2016-03-02 (196 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/gtk/+bug/1623763/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
