GTKD - CSS class color "flash" delay

[TheDGuy via Digitalmars-d-learn]

On Saturday, 25 June 2016 at 11:45:40 UTC, Mike Wey wrote:
>
>
> You should change the css class in the timeout_delay function.
>
> It's called by the GTK main loop every time the amount of 
> seconds passed to the constructor has passed. And return true 
> if you want to continue to flash the button, and false to stop.
>
> Also don't sleep in the timeout function, the main loop should 
> take care of that, currently you are blocking the main thread 
> for 5 seconds.

Thanks for your answer.
I have to pass the Button object to my timeout function to change 
the CSS class. But how do i do that within the Timeout 
constructor?