xubuntu@xubuntu:~$ sudo apt-get install xfpanel-switch 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be upgraded:
  xfpanel-switch
1 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
Need to get 20.4 kB of archives.
After this operation, 39.9 kB of additional disk space will be used.
Get:1 http://ppa.launchpad.net/xubuntu-dev/xubuntu-staging/ubuntu/ wily/main xfpanel-switch all 1.0.2-0ubuntu1 [20.4 kB]
Fetched 20.4 kB in 0s (55.0 kB/s)   
(Reading database ... 193929 files and directories currently installed.)
Preparing to unpack .../xfpanel-switch_1.0.2-0ubuntu1_all.deb ...
Unpacking xfpanel-switch (1.0.2-0ubuntu1) over (1.0-0ubuntu1) ...
Processing triggers for gnome-menus (3.13.3-6ubuntu1) ...
Processing triggers for desktop-file-utils (0.22-1ubuntu3) ...
Processing triggers for mime-support (3.58ubuntu1) ...
Setting up xfpanel-switch (1.0.2-0ubuntu1) ...