Thanks.  If I code the color: call after the openInWorld the button  
stills shows the default color once clicked - I'll have to look into  
that more.  Using a wrapper for the PluggableButtonMorph works, but  
then the framing has to be handled differently - I'll have to tidy that.

I'm actually looking for some clean initialization code based on a  
nice 'template' approach that I can use straight forwardly for  
teaching how to write applications.   A style of programming where  
you have to undo things that have been done elsewhere is not  
something I believe in as a matter of principle!  This overriding and  
the subsequent fixes/hacks are not conducive to easy teaching - or  
easy program development come to that.

I think the best solution is probably for me not to use SystemWindow  
but instead have a different class (maybe a new subclass of  
SystemWindow called (maybe) ApplicationWindow) which does not have  
the 'overruling' that comes from the setWindowColor: method.  An  
alternative might be that there could be another Preference for  
SystemWindow so that the overriding can be switched off or the  
updating be optionally requested from the model when needed.

Comments welcome.