Unity doesn't ship with a keyboard modifiers state indicator by default, so Abdellah Chelli has recently created such an indicator, called Xkbmod Indicator, useful for users with disabilities who need use sticky keys.
Xkbmod Indicator indicates the state of the following modifier keys: Shift, Caps Lock, Ctrl, Alt, Num Lock, Super and AltGr (and locked AltGr; a red dot means locked).
In its current state, Xkbmod Indicator is considered a prototype, so it may not work as expected, but I didn't encounter any major issues in my test. There is an issue which depends on the theme you're using though: by default, Xkbmod Indicator only supports themes with dark panels such as Ambiance.
However, you can get Xkbmod Indicator to work with any theme if you set it to use labels (text) instead of an image for the indicator. But in that case, only the active keyboard modifiers will be displayed, which will make the indicators shift each time you press a keyboard modifier so that might be annoying:
If you want the indicator to use labels instead of an image, launch Xkbmod Indicator with the "-l" parameter (for instance, if you've used our package, copy the indicator-xkbmod.desktop file from /etc/xdg/autostart/ to ~/.config/autostart/ and change the "Exec" line in this file so that it launches "/usr/bin/indicator-xkbmod -l").
Install Xkbmod Indicator in Ubuntu
To install Xkbmod Indicator in Ubuntu, you can use the main WebUpd8 PPA. Add the PPA and install Xkbmod Indicator by using the following commands:
Or, if you don't want to add our PPA, simply download the Xkbmod Indicator files from HERE.
sudo add-apt-repository ppa:nilarimogard/webupd8 sudo apt-get update sudo apt-get install indicator-xkbmod
Once installed, log out and log back in and Xkbmod Indicator should start automatically.
To grab the source code, report bugs and so on, visit the Xkbmod Indicator GitHub page.