When ibus-pinyin is activated, selecting text in firefox deletes text

I have tested some other GTK programs, only a combination of Firefox and ibus-pinyin causes this problem. I am on Ubuntu 14.10, and this bug is always reproducible. I think both ibus and firefox has upgraded for several times, but the problem persists. Before I upgrade to 14.10, I did not encounter this problem in 14.04. I upgraded long before using the update manager.

ibus-pinyin:
  Installed: 1.5.0-3ubuntu1
  Candidate: 1.5.0-3ubuntu1
  Version table:
 *** 1.5.0-3ubuntu1 0
        500 http://us.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

ibus:
  Installed: 1.5.8-2ubuntu2
  Candidate: 1.5.8-2ubuntu2
  Version table:
 *** 1.5.8-2ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages
        100 /var/lib/dpkg/status

firefox:
  Installed: 36.0+build2-0ubuntu0.14.10.4
  Candidate: 36.0+build2-0ubuntu0.14.10.4
  Version table:
 *** 36.0+build2-0ubuntu0.14.10.4 0
        500 http://us.archive.ubuntu.com/ubuntu/ utopic-updates/main amd64 Packages
        500 http://us.archive.ubuntu.com/ubuntu/ utopic-security/main amd64 Packages
        100 /var/lib/dpkg/status
     33.0+build2-0ubuntu0.14.10.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ utopic/main amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: ibus 1.5.8-2ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-31.41-lowlatency 3.16.7-ckt5
Uname: Linux 3.16.0-31-lowlatency x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.7-0ubuntu8.2
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Mar 8 14:07:46 2015
InstallationDate: Installed on 2014-10-28 (130 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: ibus
UpgradeStatus: Upgraded to utopic on 2015-01-30 (37 days ago)