Updating a viewport

[Stéphane Albin <salbin emse fr>]

Hi,

In gtk1.2,
I have a GtkDrawingArea inside a GtkViewport. The size of the drawing
area may change even if the viewport doesn't change.
So, when I redraw a smaller image, a part of the preceding one is still
visible.
How can I clear this part or affect the same colour as background ?

TIA,
Stéphane.
-- 
                Stéphane ALBIN
Laboratoire d'Images de Synthèse de St-Etienne
Centre SIMMO - Ecole des Mines de Saint-Etienne
Tel: (33) 4 77 42 01 78 - Fax:  (33) 4 77 42 66 66
e-mail: Stephane Albin emse fr - www: http://perso.wanadoo.fr/salbin/