Getting the "y" argument of a Widget

[Danie Roux <s9806673 student up ac za>]

Hi all, 

I want the y argument of a widget. 

I think I need to call 

gtk_widget_get(widget, arg) 

where arg is a GtkArg struct with it's type set to GTK_TYPE_STRING and the
name to y.

But when I compile this I get "Size of struct unknown" or something to
that effect.

Can someone please tell me what I'm missing?

Thanks!

Danie.