I just downloaded latest gtk3 with glib (glib-2.41.2 and gtk+-3.13.4) and I noticed immediately that the console is full of useless runtime warnings similar to the one below, when I run an application X.

> GLib-GObject-WARNING **: The property GtkImage:stock is deprecated and
> shouldn't be used anymore. It will be removed in a future version.

This is completely useless for various reasons:
- how am I, as a *regular user* of application X, supposed react to these
  warnings? I cannot do anything about it, as a *regular user*;
- what if the application X supports also older gtk/glib/... where these
  deprecated properties are still used and valid?
- what if it comes from an .ui file definition? (it makes the .ui files
  useless too, in some extent);
- my system logs are full of these useless warnings, which doesn't eat only
  my SSD disk space, but also wastes space in bug reports from tools which
  can upload these system logs as well;
- what is wrong with compiler warnings? That's the way how *a developer* of
  the application X is supposed to be notified about upcoming changes; the
  runtime is not meant for this at all;
- these useless warnings make the application X unusable with fatal-warnings,
  while it can still be completely free of any issue otherwise (note of
  the second ball, it can be valid to use the "old" properties)

I am aware of G_ENABLE_DIAGNOSTIC=0, but are you going to set this environment variable in each single destination where the new library can be deployed? Definitely not.

I suggest to change defaults, if you do not want to get rid of it completely. The default should be "off" state and *developers* can turn it on on demand, when *they want* to actually diagnose the code. Having this on by default brings just a bad experience to *users*.