ibus-ui-gtk3 crashed with SIGTRAP right after changing keybinding in Kubuntu 14.10

## Reproduce steps
1. Launch ibus-setup
2. Change switch input method keybinding to <ctrl><shift><release>
3. Restart ibus

## Expected behavior
ibus running normally with the new keybinding setuped.

## Current behavior
ibus crashed right after restarting with
```
traps: ibus-ui-gtk3[4182] trap int3 ip:7fb5db001d30 sp:7fffb2526670 error:0
```
in kernel log

## Stacktrace
`````
(gdb) run
Starting program: /usr/lib/ibus/ibus-ui-gtk3
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffedbad700 (LWP 6386)]
[New Thread 0x7fffed3ac700 (LWP 6387)]
[New Thread 0x7fffecbab700 (LWP 6389)]

(ibus-ui-gtk3:6382): Gdk-ERROR **: The program 'ibus-ui-gtk3' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadValue (integer parameter out of range for operation)'.
  (Details: serial 647 error_code 2 request_code 131 (XInputExtension) minor_code 54)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Program received signal SIGTRAP, Trace/breakpoint trap.
g_logv (log_domain=0x7ffff744c166 "Gdk", log_level=G_LOG_LEVEL_ERROR, format=<optimized out>,
    args=args@entry=0x7fffffffd510) at /build/buildd/glib2.0-2.42.0/./glib/gmessages.c:1046
1046 /build/buildd/glib2.0-2.42.0/./glib/gmessages.c: 沒有此一檔案或目錄.
(gdb) bt
#0 g_logv (log_domain=0x7ffff744c166 "Gdk", log_level=G_LOG_LEVEL_ERROR,
    format=<optimized out>, args=args@entry=0x7fffffffd510)
    at /build/buildd/glib2.0-2.42.0/./glib/gmessages.c:1046
#1 0x00007ffff55f7f6f in g_log (log_domain=log_domain@entry=0x7ffff744c166 "Gdk",
    log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=format@entry=0x7ffff74681d7 "%s")
    at /build/buildd/glib2.0-2.42.0/./glib/gmessages.c:1079
#2 0x00007ffff742397b in _gdk_x11_display_error_event (display=display@entry=0x687000,
    error=error@entry=0x7fffffffd6c0)
    at /build/buildd/gtk+3.0-3.12.2/./gdk/x11/gdkdisplay-x11.c:2536
#3 0x00007ffff742c351 in gdk_x_error (xdisplay=0x6796e0, error=0x7fffffffd6c0)
    at /build/buildd/gtk+3.0-3.12.2/./gdk/x11/gdkmain-x11.c:302
#4 0x00007ffff67547ed in _XError (dpy=dpy@entry=0x6796e0, rep=rep@entry=0x80b970)
    at ../../src/XlibInt.c:1463
#5 0x00007ffff67517e7 in handle_error (dpy=dpy@entry=0x6796e0, err=0x80b970,
    in_XReply=in_XReply@entry=1) at ../../src/xcb_io.c:213
#6 0x00007ffff67528b1 in _XReply (dpy=dpy@entry=0x6796e0, rep=rep@entry=0x7fffffffd880,
    extra=extra@entry=0, discard=discard@entry=0) at ../../src/xcb_io.c:699
#7 0x00007ffff651070d in _XIPassiveGrabDevice (dpy=0x6796e0, deviceid=1,
    grabtype=grabtype@entry=1, detail=<optimized out>, grab_window=157, cursor=cursor@entry=0,
    grab_mode=1, paired_device_mode=1, owner_events=1, mask=0x7fffffffd980, num_modifiers=8,
    modifiers_inout=0x80b9a0) at ../../src/XIPassiveGrab.c:88
#8 0x00007ffff651086c in XIGrabKeycode (dpy=<optimized out>, deviceid=<optimized out>,
    keycode=<optimized out>, grab_window=<optimized out>, grab_mode=<optimized out>,
    paired_device_mode=<optimized out>, owner_events=1, mask=0x7fffffffd980, num_modifiers=8,
    modifiers_inout=0x80b9a0) at ../../src/XIPassiveGrab.c:130
#9 0x000000000040dffe in ?? ()
#10 0x0000000000411385 in ?? ()
#11 0x0000000000412d66 in ?? ()
#12 0x0000000000408f5d in ?? ()
#13 0x00007ffff5bcf274 in emit_signal_instance_in_idle_cb (data=0x7fffe80088a0)
    at /build/buildd/glib2.0-2.42.0/./gio/gdbusconnection.c:3753
#14 0x00007ffff55f0b6d in g_main_dispatch (context=0x673e20)
    at /build/buildd/glib2.0-2.42.0/./glib/gmain.c:3111
#15 g_main_context_dispatch (context=context@entry=0x673e20)
    at /build/buildd/glib2.0-2.42.0/./glib/gmain.c:3710
#16 0x00007ffff55f0f48 in g_main_context_iterate (context=0x673e20, block=block@entry=1,
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.42.0/./glib/gmain.c:3781
#17 0x00007ffff55f1272 in g_main_loop_run (loop=0x6c54d0)
    at /build/buildd/glib2.0-2.42.0/./glib/gmain.c:3975
#18 0x00007ffff7844045 in gtk_main () at /build/buildd/gtk+3.0-3.12.2/./gtk/gtkmain.c:1192
#19 0x000000000040945e in ?? ()
#20 0x00000000004097f8 in ?? ()
#21 0x0000000000408c30 in ?? ()
#22 0x00007ffff4fe5ec5 in __libc_start_main (main=0x408c20, argc=1, argv=0x7fffffffdd28,
    init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>,
    stack_end=0x7fffffffdd18) at libc-start.c:287
#23 0x0000000000408c60 in ?? ()
(gdb)
`````

## Workarounds
Currently there's no workaround, set keybinding back to default value didn't work.

## Upstream bugreport
https://code.google.com/p/ibus/issues/detail?id=1748

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: ibus 1.5.8-2ubuntu2
ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
Uname: Linux 3.16.0-24-generic x86_64
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Nov 11 01:54:35 2014
InstallationDate: Installed on 2014-11-10 (0 days ago)
InstallationMedia: Kubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
SourcePackage: ibus
UpgradeStatus: No upgrade log present (probably fresh install)
---
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: i386
CurrentDesktop: KDE
DistroRelease: Ubuntu 14.04
InstallationDate: Installed on 2013-03-08 (612 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release i386 (20121017.2)
NonfreeKernelModules: nvidia
Package: ibus 1.5.5-1ubuntu3
PackageArchitecture: i386
ProcVersionSignature: Ubuntu 3.16.0-24.32-lowlatency 3.16.4
Tags: third-party-packages trusty
Uname: Linux 3.16.0-24-lowlatency i686
UpgradeStatus: Upgraded to trusty on 2014-04-19 (206 days ago)
UserGroups: adm cdrom davfs2 debian-tor dialout disk floppy fuse gdm hadoop hbase kvm libvirtd lightdm lp lpadmin mediatomb pcscd plugdev root sudo tape tty vboxusers video wireshark www-data
_MarkForUpload: True
---
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
CurrentDesktop: Unity
DistroRelease: Ubuntu 14.10
InstallationDate: Installed on 2014-11-10 (1 days ago)
InstallationMedia: Kubuntu 14.10 "Utopic Unicorn" - Release amd64 (20141022.1)
Package: ibus 1.5.8-2ubuntu2
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
Tags: utopic
Uname: Linux 3.16.0-24-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True