scrolled window with viewport example

[dhendrix socrates Berkeley EDU]

Thanks in advance for taking the time to read this.  Here is a very short
code to produce a scrolled window with a child that IS NOT a table.  You
see almost every example on the web uses tables, and they seem to work.
But if you want to have a drawable area in a scrolled window (imagine if
you wanted to zoom in on an picture), it doesn't seem to work.

The scrollbars are always as big as the mainwindow, and can hence never
move!  How can I make this scrolled window a scrolling window?