A flashing button

[Antony Stace <antony claire co jp>]

 hi folks

I need to create a special type of button.  The button will have a
picture(1) on it which I will make, when the user clicks on the button
the button should change to another picture(2) which I will supply, when
the user releases the mouse button picture(1) will be displayed again. 
This button can also be in two states, in state one it will behave like
a normal button, when in the other state it will blink between
picture(1) and picture(3).  What would be the best way to do this.

Cheers

Antony