I am noticing my language input keeps on jumping back to U.S. instead of Google's Alphanumeric input. Can anyone please tell me how to set Google IME's Alphanumeric input as primary input source, and remove U.S. input all together? The U.S. input source is grey'ed out so I cannot just uncheck it. This is how the Input Source section looks like:
http://misc.chiisana.net/vcapture/InputSources.png
I don't think you can disable US. OS X always keeps one Apple keyboard like that active by default. This might be to avoid users accidentally winding up with no keyboard able to enter ascii characters for passwords, etc.
In order to remove US input source, for the adventurous few (see warning in previous reply), here are the procedures:
1) Make a backup of your preferences, via Time Machine or otherwise.
2) Download a plist editor.
3) Uncheck ALL input sources in System Preferences > Languages & Text > Input sources EXCEPT for 2, the one you want as primary, and the one you cannot remove. You can add them back later, just disable them for now.
3) Open ~/Library/Preferences/ByHost/com.apple.HIToolbox.<some string>.plist *<some string> is a HEX string (hopefully) unique to your machine host using your plist editor.
4) Under "AppleEnabledInputSources", delete the first node... should be something like:
<dict>
<key>InputSourceKind</key>
<string>Keyboard Layout</string>
<key>KeyboardLayout ID</key>
<integer>0</integer>
<key>KeyboardLayout Name</key>
<string>U.S.</string>
</dict>
5) Save, Login and out of your user, and you're done.
I'd imagine that's only at the login level, once the user is logged in, the preference of which IME to active/disable should be up to the user to decide?