simple example of gtk-scrolled-window not working

[David Morse <dcmorse gmail com>]

I took the "hello world" example from the gtk+2 tutorial, but with a
gtk_scrolled_window.  The resulting program runs fine except that
THERE'S NO WINDOW VISIBLE ON THE SCREEN!  What am I doing wrong?

The source is attached, you can quickly find the changed lines because
the originals are commented with the c++ '//' comments.  Basically I
replaced gtk_window_new() with gtk_scrolled_window_new(), and also
gtk_container_add() with gtk_scrolled_window_add_with_viewport().