X freezes when notify OSD appears while in full-screen openGL game

when I want to change volume while I'm running a full-screen app the whole GUI freezes and I have to manually open a terminal to restart X11.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: notify-osd 0.9.35+15.10.20151014-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Oct 23 12:15:29 2015
DesktopSession: 'ubuntu'
GtkTheme: 'Ambiance'
IconTheme: 'ubuntu-mono-dark'
InstallationDate: Installed on 2014-11-08 (348 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
MachineType: Notebook W65_67SF
ProcEnviron:
 LANGUAGE=nl_NL
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=nl_NL.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-16-generic root=UUID=c1033a27-1470-4958-aa0f-9c93f0858e3f ro quiet splash
RelatedPackageVersions:
 xserver-xorg 1:7.7+7ubuntu4
 libgl1-mesa-glx 11.0.2-1ubuntu4
 libdrm2 2.4.64-1
 xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
 xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
SourcePackage: notify-osd
UpgradeStatus: Upgraded to wily on 2015-10-19 (3 days ago)
dmi.bios.date: 08/25/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1.03.04
dmi.board.asset.tag: Tag 12345
dmi.board.name: W65_67SF
dmi.board.vendor: Notebook
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: Notebook
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.03.04:bd08/25/2014:svnNotebook:pnW65_67SF:pvrNotApplicable:rvnNotebook:rnW65_67SF:rvrNotApplicable:cvnNotebook:ct9:cvrN/A:
dmi.product.name: W65_67SF
dmi.product.version: Not Applicable
dmi.sys.vendor: Notebook