Detect Caps Lock state

[local function declaration]
FUNCTION int GetKeyState(int keystatus) LIBRARY "user32.dll"
[powerscript]
int li_keystate
li_keystate = GetKeyState(20)
IF li_keystate = 1 THEN
MessageBox("", "CAPS on")
ELSEIF li_keystate = 0 THEN
MessageBox("", "CAPS off")
END IF