Created attachment 289174 [details]
little test program just launching a FileChooserDialog

Since the latest update under Ubuntu to libgtk-3 version 3.10.8, a GTK application fails when using gtk_file_chooser_dialog() and the homedirectory referenced by the $HOME environment variable is not readable.
This can easily be reproduced by calling the attached little test program by the following command line as a normal user:

$ HOME=/root ./hello-world 

(hello-world:4704): Gtk-CRITICAL **: Unable to create user data directory '/root/.local/share' for storing the recently used files list: Permission denied
**
Gtk:ERROR:/build/buildd/gtk+3.0-3.10.8/./gtk/gtkrecentmanager.c:617:gtk_recent_manager_set_filename: assertion failed: (priv->filename != NULL)
Aborted


This issue does not occur on older libgtk version such as 3.4.2 (Debian Wheezy)
Even newer versions such as 3.12.4 (Debian Jessie) is also affected.

The severity is set to critical because a segmentation fault of a GTK application can be triggered by setting an environment variable.
If the home directory is not readable, a GTK application should never segfault, rather than catching the error.