Checks Control key
──────────────────────────────────────────────────────────────────────────────

 Syntax

        GT_isCtrl() --> lRet

 Arguments:

      None

 Returns:

      lRet    -       TRUE if Ctrl is being pressed, otherwise FALSE

 Description:

      Checks status of the Ctrl Key

 Examples:

      if GT_isCtrl()
          ? "Get your grubby fingers off the control key."
      endif

 Source: CTRL.ASM

 Author:  Andy M Leighton