After following the discussion for some time, I have the impression that there are some smalltalkers suffering similar usability problems like my friend and me and some more or less enjoy the actual state.
Dolphin 6 Professional introduced IdeaSpace. With that you can have both - single windows and tabbed windows.
It's up to the user to either open windows outside IdeaSpace as independent windows or inside IdeaSpace as tabbed windows.
Having the free choice is a good thing. Especially if you don't want to alienate newcomers that are used to use tabbed windows. I like this approach.

I haven't looked at TWM yet due to lack of time. I am hardly able to read the mail traffic in the evenings.
But I asked my friend to have a look at it. He promised to do so although it's not suited to Pharo 1.2.1.
As Pharo 1.3 is not yet stable I fear that he might have new problems in other areas.

What strikes me during this discussion is that nobody seem to have the same problem with window sizes and positions.
I don't like RealEstateAgent and I don't think that a revamped one will solve the problems. At least as long it doesn't provide the possibility
to set sizes on the fly. No algorithm can guess the requirements of all users.
I also haven't heard about applications written in Squeak or Pharo and what about user thereof think about the usability. IMO there is a lack of
an appropriate framework for dealing with such things. Or is everybody developing web applications nowadays?

I have a hard time to promote Smalltalk because of its actual state. I always tell people about my favorite programming
language, but I also tell them that alas there is no good implementation of it available. This is sad but true, even if Pharo and Squeak made
big progress during the last months. Both, Squeak and Pharo, aren't products but just tools. And that makes a big difference.
The commercial products have characteristics that make them not very attractive to people not yet involved. Despite Dolphin they all have
dated user interfaces, too. When I try to convince people to have a look at Dolphin they typically tell me: very nice but it seems to be dead already.

Regards,
Andreas