gtkD: How to paint to screen for animation

[Michelle Long via Digitalmars-d-learn]

I've added a function to addOnDraw for a DrawingArea and it 
paints using the code I have when I resize.

I added a queueDraw in threadsAddIdle and it seems to draws the 
screen immediately but it does not seem to be called again.

If I put queueDraw inside the addOnDraw routine then the 
animation works but it is quite slow, about 1 fps and cpu usage 
is 100% without it, it is 0%.