Blinking button?

Hi, maybe somebody can help my with blinking button.In general i want to make button blinking when player playing .Do not know how to do that.Lets say if i do with two button images ledlighton.jpg and ledlightof.jpg to channging in clock seconds speed.I need not color changing yelow to black but picture changing or dimming.Or maybe possible somehow make response button on click dimming (already in MIT appinventor).Any ideas or directions what i can try?Or maybe that not possible on MIT app inventor?Thank you in advance

-- 

use a clock component and an if block like this

if Button1.Image =  ledlighton.jpg

then 

  Button1.Image =  ledlightoff.jpg
  Button2.Image =  ledlighton.jpg

else

  Button1.Image =  ledlighton.jpg
  Button1.Image =  ledlightoff.jpg

-- 

O  thank you! Learning not easy thing :)

--