Possible typo in item-grid code?

[Nick Lamb <njl98r ecs soton ac uk>]

I am looking at various parts of Gnumeric while trying to learn how
GTK+ objects in GnomeCanvas work.

In src/item-grid.c I read

static GnomeCanvasItem *item_grid_parent_class;

But now that I understand what it's for, this seems stupid. Shouldn't it
be either:

static GnomeCanvasItemClass *item_grid_parent_class;
OR
static GtkObjectClass *item_grid_parent_class;

There are lots of casts in this source file which seem to be trying to
hack around the basic problem that we're using this pointer to point
at entirely the wrong kind of structure, yes?

Nick.