What's the output of /usr/libexec/gnome-rr-debug on that machine (you can Ctrl+C once it's listed all the displays).

Hi Bastien, here is my output :

deevad@workstation:~$ /usr/lib/gnome-rr-debug
bash: /usr/lib/gnome-rr-debug: No such file or directory

deevad@workstation:~$ locate gnome-rr-debug
/usr/lib/libgnome-desktop-3-10/gnome-rr-debug
/usr/lib/libgnome-desktop-3-7/gnome-rr-debug

deevad@workstation:~$ /usr/lib/libgnome-desktop-3-10/gnome-rr-debug
[DVI-D-0]
	connected: 1
	builtin (laptop): 0
	primary: 1
	id: 0
	dimensions: 546x352	edid: 128 bytes [0:255:255:255]
[DVI-D-1]
	connected: 1
	builtin (laptop): 0
	primary: 0
	id: 1
	dimensions: 432x324	edid: 128 bytes [0:255:255:255]
^C

deevad@workstation:~$ /usr/lib/libgnome-desktop-3-7/gnome-rr-debug
[VGA-0]
	connected: 0
	laptop: 0
	primary: 0
	id: 637
[HDMI-0]
	connected: 0
	laptop: 0
	primary: 0
	id: 638
[DVI-D-0]
	connected: 1
	laptop: 0
	primary: 1
	id: 639
	edid: 128 bytes [0:255:255:255]
[DVI-D-1]
	connected: 1
	laptop: 0
	primary: 0
	id: 659
	edid: 128 bytes [0:255:255:255]

deevad@workstation:~$

You'll have to clarify the versions of everything you're using. gnome-control-center 3.12.x requires gnome-desktop 3.11.3, so I'm not sure how you get gnome-desktop 3.10 with that. (The debug output of gnome-rr-debug is slightly longer than that)

What are the versions of gnome-settings-daemon, gnome-control-center and gnome-desktop?

Hi Bastien,

* gnome-settings-daemon : 3.12.2-0ubuntu1~trusty1
* gnome-control-center : ( libgnome-control-center1 ) 1:3.12.1-0ubuntu1~trusty3
* gnome-desktop : ( libgnome-desktop-3-10 , and libgnome-desktop-3-7 ) 3.12.2-0ubuntu1~trusty2 ,  and 3.8.4-0ubuntu3

It sounds like "Ubuntu Gnome" 14.04 packagers are not helping. It's hard here to know what version is packaged ; the package names are branded 3.12.* anyway in my package manager (synaptic). Also, running the process from command line, with --debug flag or --help don't print version number.

(In reply to comment #4)
> Hi Bastien,
> 
> * gnome-settings-daemon : 3.12.2-0ubuntu1~trusty1
> * gnome-control-center : ( libgnome-control-center1 ) 1:3.12.1-0ubuntu1~trusty3
> * gnome-desktop : ( libgnome-desktop-3-10 , and libgnome-desktop-3-7 )
> 3.12.2-0ubuntu1~trusty2 ,  and 3.8.4-0ubuntu3

It's gnome-desktop 3.12, so that's not the problem.

Can you please grab:
https://git.gnome.org/browse/gnome-desktop/plain/libgnome-desktop/gnome-rr-debug.c

And compile it with:
gcc -o gnome-rr-debug `pkg-config --libs --cflags gnome-desktop-3.0` gnome-rr-debug.c

Then launch:
./gnome-rr-debug
As you would the previous time.

(In reply to comment #0)
> 1)Spam notifications to calibrate :
> ===================================
> This happen because of a new rule in 3.12 : propose a calibration when the
> resolution has changed. To compare if the resolution of a Cintiq changed, GNOME
> save in org.gnome.settings-daemon.peripherals.wacom then
> last-calibrated-resolution the resolution of the Cintiq ( in my case 1600x1200,
> a Cintiq21UX ). This number is compared -I guess- to the desktop resolution.

It's not. It's the resolution of the screen the Cintiq is mapped to:
https://git.gnome.org/browse/gnome-settings-daemon/tree/plugins/wacom/gsd-wacom-manager.c#n1531

> In
> my case 1920x1200+1600x1200, so 3520 x 1200 ( I use a twinview dual-screen
> Nvidia ). I could guess this, because if you change in Dconf 1600x1200 to 3520
> x 1200 the notification spam is stopping.

It sounds like the Cintiq isn't mapped to any monitor, bizarrely enough. What's the output of "gsd-list-wacom" (it's in /usr/lib... somewhere as well).

> 2)Tablet mapping to a single-screen doesn't load at start-up :

It's one bug per bug usually, but as this seem related, let's fix the first one first.

> Can you please grab:
> https://git.gnome.org/browse/gnome-desktop/plain/libgnome-desktop/gnome-rr-debug.c
> And compile it with:
> gcc -o gnome-rr-debug `pkg-config --libs --cflags gnome-desktop-3.0` gnome-rr-debug.c
> Then launch:
> ./gnome-rr-debug
> As you would the previous time.
Ok, I tried, but it didn't succeed to compile :
wget https://git.gnome.org/browse/gnome-desktop/plain/libgnome-desktop/gnome-rr-debug.c
Package gnome-desktop-3.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `gnome-desktop-3.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'gnome-desktop-3.0' found
gnome-rr-debug.c:23:22: fatal error: gdk/gdkx.h: No such file or directory
 #include <gdk/gdkx.h>
                      ^
compilation terminated.


> It sounds like the Cintiq isn't mapped to any monitor, bizarrely enough. What's
the output of "gsd-list-wacom" (it's in /usr/lib... somewhere as well).
Here is the /usr/lib/gnome-settings-daemon/gsd-list-wacom
http://pastebin.com/1BnhPfZf

(In reply to comment #6)
> > Can you please grab:
> > https://git.gnome.org/browse/gnome-desktop/plain/libgnome-desktop/gnome-rr-debug.c
> > And compile it with:
> > gcc -o gnome-rr-debug `pkg-config --libs --cflags gnome-desktop-3.0` gnome-rr-debug.c
> > Then launch:
> > ./gnome-rr-debug
> > As you would the previous time.
> Ok, I tried, but it didn't succeed to compile :
> wget
> https://git.gnome.org/browse/gnome-desktop/plain/libgnome-desktop/gnome-rr-debug.c
> Package gnome-desktop-3.0 was not found in the pkg-config search path.

Install the development package.

> Install the development package.
Ok, I opened synaptic and tryied to install the max of *-dev packages things related with this issue. 
Problem : Gnome-devel and Gnome-core-devel is still available in version 3.8+4ubuntu3 ; and synaptic refuse me to install them anyway ( broken dependencies warning ). I guess this two packages are blocked to this previous version because it's what the Ubuntu dev are using for the Unity main desktop. 
Would it mean I reached a dead-end ? I wouldn't be surprise...

Here are additionnal infos; 

I installed the following packages ; it's what I could do :
===========================================================
accerciser (3.12.0-1)
anjuta (2:3.11.90-0ubuntu1~trusty1)
anjuta-common (2:3.11.90-0ubuntu1~trusty1)
autoconf (2.69-6)
autogen (1:5.18-2ubuntu2)
automake (1:1.14.1-2ubuntu1)
autopoint (0.18.3.1-1ubuntu3)
autotools-dev (20130810.1)
devhelp (3.12.1-0ubuntu1~trusty1)
devhelp-common (3.12.1-0ubuntu1~trusty1)
docbook-dsssl (1.79-7ubuntu1)
gir1.2-gtk-2.0 (2.24.23-0ubuntu1.1)
glade (3.18.3-1~trusty1)
gnome-api-docs (1:3.8+4ubuntu3)
gnome-common (3.12.0-1~trusty1)
gnome-control-center-dev (1:3.12.1-0ubuntu1~trusty3)
gnome-devel-docs (3.8.1-1)
gnome-platform-devel (1:3.8+4ubuntu3)
gnome-settings-daemon-dev (3.12.2-0ubuntu1~trusty1)
gsettings-desktop-schemas-dev (3.12.0-0ubuntu1~trusty1)
gstreamer1.0-doc (1.2.4-0ubuntu1)
gtk-doc-tools (1.20-1ubuntu1)
intltool (0.50.2-2)
ipython3 (1.2.1-2)
jade (1.2.1-47.3ubuntu1)
libanjuta-3-0 (2:3.11.90-0ubuntu1~trusty1)
libapr1 (1.5.0-1)
libaprutil1 (1.5.3-1)
libatk1.0-doc (2.12.0-1ubuntu1~trusty1)
libcairo2-doc (1.13.0~20140204-0ubuntu1)
libcanberra-doc (0.30-0ubuntu3)
libclutter-1.0-dev (1.16.4-0ubuntu2)
libclutter-1.0-doc (1.16.4-0ubuntu2)
libclutter-gtk-1.0-dev (1.4.4-3ubuntu2)
libclutter-gtk-1.0-doc (1.4.4-3ubuntu2)
libcogl-dev (1.16.2-1)
libcogl-doc (1.16.2-1)
libcogl-pango-dev (1.16.2-1)
libdbus-glib-1-dev (0.100.2-1)
libdevhelp-3-2 (3.12.1-0ubuntu1~trusty1)
libgail-3-dev (3.12.2-0ubuntu4~trusty1)
libgail-3-doc (3.12.2-0ubuntu4~trusty1)
libgail-dev (2.24.23-0ubuntu1.1)
libgail-doc (2.24.23-0ubuntu1.1)
libgbm-dev (10.1.3-0ubuntu0.1)
libgda-5.0-4 (5.2.2-1)
libgda-5.0-common (5.2.2-1)
libgdk-pixbuf2.0-doc (2.30.7-0ubuntu1)
libgdl-3-5 (3.8.1-2ubuntu1)
libgdl-3-common (3.8.1-2ubuntu1)
libgdm-dev (3.12.2-0ubuntu1~trusty1)
libgladeui-2-6 (3.18.3-1~trusty1)
libgladeui-common (3.18.3-1~trusty1)
libglib2.0-doc (2.40.0-2)
libgnome-desktop-3-dev (3.12.2-0ubuntu1~trusty2)
libgnome-menu-3-dev (3.10.1-0ubuntu2)
libgstreamer1.0-dev (1.2.4-0ubuntu1)
libgtk-3-doc (3.12.2-0ubuntu4~trusty1)
libgtk2.0-dev (2.24.23-0ubuntu1.1)
libgtk2.0-doc (2.24.23-0ubuntu1.1)
libgtksourceview-3.0-dev (3.12.1-0ubuntu1~trusty1)
libgtksourceview-3.0-doc (3.12.1-0ubuntu1~trusty1)
libjson-glib-dev (1.0.0-1~trusty1)
libltdl-dev (2.4.2-1.7ubuntu1)
libnotify-doc (0.7.6-1ubuntu3)
libopts25 (1:5.18-2ubuntu2)
libopts25-dev (1:5.18-2ubuntu2)
libpango1.0-doc (1.36.3-1ubuntu1)
libserf-1-1 (1.3.3-1)
libsvn1 (1.8.8-1ubuntu3)
libtelepathy-glib-doc (0.24.0-1~trusty1)
libtool (2.4.2-1.7ubuntu1)
libvala-0.20-0 (0.20.1-2ubuntu5)
libvala-0.24-0 (0.24.0-5~14.04~valateam0)
libxml-parser-perl (2.41-1build3)
libxml2-dev (2.9.1+dfsg1-3ubuntu4.3)
libxml2-doc (2.9.1+dfsg1-3ubuntu4.3)
m4 (1.4.17-2ubuntu1)
policykit-1-doc (0.105-4ubuntu2)
python3-decorator (3.4.0-2build1)
python3-simplegeneric (0.8.1-1)
valac-0.20 (0.20.1-2ubuntu5)
valac-0.20-vapi (0.20.1-2ubuntu5)


Second attempt :
================

deevad@workstation:~/Software/lib-gnome-desktop$ gcc -o gnome-rr-debug `pkg-config --libs --cflags gnome-desktop-3.0` gnome-rr-debug.c
/tmp/ccMkjjQl.o: In function `print_output':
gnome-rr-debug.c:(.text+0x29): undefined reference to `gnome_rr_output_get_name'
gnome-rr-debug.c:(.text+0x3b): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x58): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x67): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x7b): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x87): undefined reference to `gnome_rr_output_is_builtin_display'
gnome-rr-debug.c:(.text+0x98): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0xa4): undefined reference to `gnome_rr_output_get_is_primary'
gnome-rr-debug.c:(.text+0xb5): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0xc1): undefined reference to `gnome_rr_output_get_id'
gnome-rr-debug.c:(.text+0xd2): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0xe9): undefined reference to `gnome_rr_output_get_physical_size'
gnome-rr-debug.c:(.text+0x100): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x10c): undefined reference to `gnome_rr_output_get_min_backlight_step'
gnome-rr-debug.c:(.text+0x11a): undefined reference to `gnome_rr_output_get_backlight'
gnome-rr-debug.c:(.text+0x12d): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x140): undefined reference to `gnome_rr_output_get_edid_data'
gnome-rr-debug.c:(.text+0x19f): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x1b7): undefined reference to `gnome_rr_output_get_ids_from_edid'
gnome-rr-debug.c:(.text+0x1d5): undefined reference to `g_print'
gnome-rr-debug.c:(.text+0x1e1): undefined reference to `g_free'
gnome-rr-debug.c:(.text+0x1ed): undefined reference to `g_free'
gnome-rr-debug.c:(.text+0x1f9): undefined reference to `g_free'
gnome-rr-debug.c:(.text+0x208): undefined reference to `g_print'
/tmp/ccMkjjQl.o: In function `screen_changed':
gnome-rr-debug.c:(.text+0x22e): undefined reference to `g_print'
/tmp/ccMkjjQl.o: In function `main':
gnome-rr-debug.c:(.text+0x2a8): undefined reference to `gtk_init'
gnome-rr-debug.c:(.text+0x2ad): undefined reference to `gdk_screen_get_default'
gnome-rr-debug.c:(.text+0x2bc): undefined reference to `gnome_rr_screen_new'
gnome-rr-debug.c:(.text+0x2eb): undefined reference to `g_log'
gnome-rr-debug.c:(.text+0x2f7): undefined reference to `g_error_free'
gnome-rr-debug.c:(.text+0x308): undefined reference to `gnome_rr_screen_list_outputs'
gnome-rr-debug.c:(.text+0x37c): undefined reference to `g_signal_connect_data'
gnome-rr-debug.c:(.text+0x3a3): undefined reference to `g_signal_connect_data'
gnome-rr-debug.c:(.text+0x3ca): undefined reference to `g_signal_connect_data'
gnome-rr-debug.c:(.text+0x3cf): undefined reference to `gtk_main'
gnome-rr-debug.c:(.text+0x3db): undefined reference to `g_object_unref'
collect2: error: ld returned 1 exit status
deevad@workstation:~/Software/lib-gnome-desktop$

Hi David, I would also find it very useful if you provided the output of:

/usr/lib/gnome-settings-daemon/gnome-settings-daemon -r --debug 

after logging in. I would be mainly interested in the whole initialization logs, after that you can keep this running on the terminal to avoid altering the current session, or log out/in to get a normally running session.

Hi Carlos, 
Unfortunately the setup was too unstable to use, and I moved to Xfce temporary with Xsetwacom and DispcalGui, and a simplier setup. I cannot test this anymore or reproduce. Bastien already read it on a Google+ I wrote; sorry for not updating this thread as well. Thanks for all helps. I'll see later if it's still happen under Fedora or Arch GNOME ; but I'll surely avoid Ubuntu-Gnome.

Closing this bug report as no further information has been provided. Please
feel free to report this to
  https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/
if you can provide the information that was asked for in a previous comment and
if this still happens in a recent and supported version. Thanks!