Keyboard Layout : the '+' icon is not always available

[Thibault D]

This happens with a 13.04 daily build on a live USB key.

1. Open Keyboard Layout (gnome-control-center > Keyboard > Layout Settings).
2. Notice that the '+' icon at the bottom-left is not available (greyed).
3. Click multiple times on the 'English' entries (US, Cameroon, UK, Ghana): the '+' icon remains unavailable.
4. Remove one of the layout entries with the '-' icon: here you go, the '+' icon is available and you can add your favorite keyboard.

What happens: the '+' icon is sometimes available
What should happen: the '+' icon is always available

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: gnome-control-center 1:3.6.3-0ubuntu16
ProcVersionSignature: Ubuntu 3.8.0-14.24-generic 3.8.4
Uname: Linux 3.8.0-14-generic i686
ApportVersion: 2.9.2-0ubuntu4
Architecture: i386
CasperVersion: 1.330
Date: Wed Mar 27 15:43:27 2013
LiveMediaBuild: Ubuntu 13.04 "Raring Ringtail" - Alpha i386 (20130326)
MarkForUpload: True
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)
usr_lib_gnome-control-center:
 activity-log-manager-control-center 0.9.4-0ubuntu6.1
 deja-dup 25.5-0ubuntu1
 gnome-control-center-signon 0.1.5-0ubuntu1
 gnome-control-center-unity 1.2daily13.02.15-0ubuntu1
 indicator-datetime 12.10.3daily13.03.07-0ubuntu1