On my Linux computer, my keyboard switches from English to Serbian when I hold the Caps Lock key. For example, to write č all I have to do is hold Caps Lock, and press the key where č is on the Serbian keyboard (in this case, they key is ; on the English keyboard). When I release Caps Lock, the keyboard "switches back" to English, so that if I press ; I get ; as desired. Super useful.
Please note that I know how to change the keyboard layout. I want to use Caps Lock as a modifier key to change the language only while being held down!
Is there a way to replicate this behavior on Windows 7 or Windows 8?
Remark: This is sometimes known as "third level" character switching (pressing shift would be second level, for example). I am also not that attached to Caps Lock; other keys will do.