Well, when TIdleTimer.AutoEnabled=False then it behaves just like normal TTimer.
If you switch to Enabled:=False and AutoEnabled:=True then (in default configuration, i.e. AutoStartEvent=itaOnIdle and AutoEndEvent=itaOnUserInput) this timer raises events on IDLE (= when nothing happens, i.e. you don't move move, no clicks, no keyboard input etc.)
I attached a small app. to testing. It is very easy, you can do it yourself too, it takes a few minutes to create such app.