Here are the details of the machine where I get a blank window.

    It's a 333MHz PowerBook G3,
    running MacOS Z1-9.0,
    with 64MB of physical memory and 128MB of virtual memory,
    8MB of video memory, 0.5MB of L2 cache,
    2MB of disc cache (presumably taken out of the 64MB). 

    There are more extensions than you can shake a stick at,
    ATI 3D & Video accelerators, Indio Video, Intel Raw Video,
    Apple QD3D HW Driver & Plugin, I've got no idea what they all are.

Here are the details about Squeak.

    Squeak is Squeak 3.5.0b4 patch level 5180; the VM that runs is
    "Squeak 3.5.0b4 classic".
    File|Get Info|Memory shows that it asks for 30 000 kB.

    When the program is running, "About this computer" shows that
    MacOS has 23.5 MB and Squeak has 29.4 MB (so it is getting the
    30 000 kB it asked for).

I have two images: Squeak3.5-5180.image (stock distribution)
and Squeak3.5-5180.1.image (made by starting up the 5180 image,
deleting Squeaky and most of the windows, opening a Package Loader,
fetching and installing Connectors1.9.sar, closing the Package Loader,
and saving the new image).

When I click in the new image, I get a white window and no evidence
of activity.  When I click on the stock image, I get a couple of
brush strokes of Squeaky and a stack trace due to some problem in BitBlt,
on top of a white window.  Click on proceed and there is no evidence of
any further activity.

But start the VM by clicking on Squeak 3.5.0Beta4.app (the actual folder;
in 9.0 it gets a Squeak icon, in 8.6 it doesn't) and chosing the image
from the file selection dialogue, and it works.  I'm very pleased that
this file selection dialogue is there; it completely fixes what used to
be a nasty problem with Squeak (students would click on the application
because that's what you _do_ on a Mac).

I spent an hour this morning demonstrating Squeak, and despite having got
the 30MB it asked for, and despite not doing much except demonstrating
the Browser and the flaps and the object catalogue, it came up with a
low space warning.  I also had a low memory warning using SqueakMap on
my desktop machine, which is also a 64MB machine, and the OS takes about
half as much memory as MacOS 9.0 does...