current-idle-timecurrent-idle-time is a built-in function in `
C source code'. (current-idle-time) Return the current length of Emacs idleness, or nil. The value when Emacs is idle is a list of four integers (HIGH LOW USEC PSEC) in the same style as (current-time). The value when Emacs is not idle is nil. PSEC is a multiple of the system clock resolution.