Comment 9 for bug 298781

This bug still exists in 2015... The problem appears with Gtk+ theme. If you change to another theme (e.g cleanlooks) this issue will disappear. (See post #1)

My PC setup:

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu Xenial Xerus (development branch)"

Using qt version 4.8.6 and the lxqt desktop in Ubuntu 16.04 (pre-release version).

~ cat /var/log/Xorg.0.log | head 23:02:09
[ 10.112]
X.Org X Server 1.17.3
Release Date: 2015-10-26
[ 10.112] X Protocol Version 11, Revision 0
[ 10.112] Build Operating System: Linux 3.19.0-33-generic x86_64 Ubuntu
[ 10.112] Current Operating System: Linux gamerpc 4.2.0-19-generic #23-Ubuntu SMP Wed Nov 11 11:39:30 UTC 2015 x86_64
[ 10.112] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.2.0-19-generic.efi.signed root=UUID=2c939427-e3f8-462d-baab-d23d2045529e ro quiet splash vt.handoff=7
[ 10.112] Build Date: 25 November 2015 04:17:13PM
[ 10.112] xorg-server 2:1.17.3-2ubuntu2 (For technical support please see http://www.ubuntu.com/support)
[ 10.112] Current version of pixman: 0.33.4

~ apt-cache show lxqt-common 23:03:56
Package: lxqt-common
Status: install ok installed
Priority: optional
Section: x11
Installed-Size: 4610
Maintainer: LXQt Packaging Team <email address hidden>
Architecture: all
Version: 0.10.0+201511240226~ubuntu16.04.1
Recommends: oxygen-icon-theme