Bug#817243: gtk3 programs segfault when a third monitor is added with a usb adapter

[coma at 19.coop]

Package: libgtk-3-0
Version: 3.18.8-1

After upgrading the library to version 3.18.8.1 i can no longer run 
GTK3 programs when using a USB to HDMI adapter to add a third monitor.

my usb adapter is a DisplayLink

#lsusb 
Bus 007 Device 008: ID 17e9:4301 DisplayLink 

To activate the third monitor i use xrandr
#xrandr --setprovideroutputsource 1 0
#xrandr --output DVI-I-1 --auto --right-of VGA1

if i turn off the monitor 
#xrandr --output DVI-I-1 --off
the problem does not occur

Downgrade the library to the previous version fixes the problem
dpkg -l | grep libgtk-3
ii libgtk-3-0:amd64   3.18.7-1 amd64        
ii libgtk-3-bin 3.18.8-1 amd64 
ii libgtk-3-common 3.18.8-1 
ii libgtk-3-dev:amd64 3.18.8-1 amd64 



-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.3.0-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libgtk-3-0 depends on:
ii  libatk-bridge2.0-0                      2.18.1-2
ii  libatk1.0-0                             2.18.0-1
ii  libc6                                   2.21-9
ii  libcairo-gobject2                       1.14.6-1
ii  libcairo2                               1.14.6-1
ii  libcolord2                              1.2.12-1
ii  libcups2                                2.1.3-3
ii  libepoxy0                               1.3.1-1
ii  libfontconfig1                          2.11.0-6.3
ii  libfreetype6                            2.6.3-3
ii  libgdk-pixbuf2.0-0                      2.32.3-1.2
ii  libglib2.0-0                            2.46.2-3
ii  libgtk-3-common                         3.18.8-1
ii  libjson-glib-1.0-0                      1.0.4-2
ii  libpango-1.0-0                          1.38.1-1
ii  libpangocairo-1.0-0                     1.38.1-1
ii  libpangoft2-1.0-0                       1.38.1-1
ii  librest-0.7-0                           0.7.93-1
ii  libsoup2.4-1                            2.52.2-1
ii  libwayland-client0                      1.9.0-1
ii  libwayland-cursor0                      1.9.0-1
ii  libwayland-egl1-mesa [libwayland-egl1]  11.1.2-1
ii  libx11-6                                2:1.6.3-1
ii  libxcomposite1                          1:0.4.4-1
ii  libxcursor1                             1:1.1.14-1+b1
ii  libxdamage1                             1:1.1.4-2+b1
ii  libxext6                                2:1.3.3-1
ii  libxfixes3                              1:5.0.1-2+b2
ii  libxi6                                  2:1.7.6-1
ii  libxinerama1                            2:1.1.3-1+b1
ii  libxkbcommon0                           0.5.0-1
ii  libxml2                                 2.9.3+dfsg1-1
ii  libxrandr2                              2:1.5.0-1
ii  shared-mime-info                        1.5-2

Versions of packages libgtk-3-0 recommends:
ii  libgtk-3-bin  3.18.8-1

Versions of packages libgtk-3-0 suggests:
ii  gvfs             1.26.2-1+b1
ii  librsvg2-common  2.40.11-2

-- no debconf information