Forcing size_allocate?

[The Surprises <thesurprises1 attbi com>]

Greetings,

I have a gnome_canvas packed into a vbox.  All drawing in the canvas is
connected to a size_allocate event because I need to know the width and
height of the area before drawing.  This works great, however upon
initial startup, I get a blank screen until I manually resize the window
to cause a size_allocate event to occur.  Is there any way to force a
size_allocate manually to get the canvas drawn by default?  I tried
emitting a size_allocate event, but this produced bogus width and height
numbers.

Thanks
Jason