How about:

SystemWindow>>initialize
	"..."
	self startSteppingSelector: #checkWorldSize stepTime: 50.

SystemWindow>>checkWorldSize
	self world extent = self extent ifFalse:[
		self extent: self world extent.
	].

Checks 20 times per sec but what the hell - if you want the window
fullscreen you probably don't care ;-)

Cheers,
  - Andreas

> -----Original Message-----
> From: squeak-dev-bounces at lists.squeakfoundation.org 
> [mailto:squeak-dev-bounces at lists.squeakfoundation.org] On 
> Behalf Of Martin Drautzburg
> Sent: Wednesday, September 17, 2003 8:06 AM
> To: The general-purpose Squeak developers list
> Subject: [Q] fullscreen application
> 
> 
> What is the best way to have a SystemWindow cover the entire squeak
> window? 
> 
> I have given it a layout frame and changed the world's layout policy
> to proporional. This basically works except the SystemWindow only
> resizes when the mouse is in the queak window, i.e. right after
> resizing the squeak window the SystemWindow is not resized until I
> enter the squeak window with the mouse.
>