Can't use mentioning feature in Google+ when input method is enabled

I tested on Firefox and Google Chromium using many available input methods, when an input method is enabled, we can't use mentioning in Google+, press +[G+ user name] and then there is no pop up appear for us to select user, but if we turn it off (press Ctrl + space) it works as usual.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: ibus 1.3.99.20110419-1ubuntu3
ProcVersionSignature: Ubuntu 3.0.0-13.22-generic 3.0.6
Uname: Linux 3.0.0-13-generic i686
ApportVersion: 1.23-0ubuntu4
Architecture: i386
Date: Wed Nov 30 23:12:47 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta i386 (20110921.2)
SourcePackage: ibus
UpgradeStatus: No upgrade log present (probably fresh install)