Scroll position problem (gtk2)

["Matthew A. Postiff" <postiffm comcast net>]

I have a GtkWidget *A that contains another GtkWidget *B. The web 
content of B changes from B_1 to B_2 when the user clicks a link inside 
of it. When I click the "Back" button in B_2, I want it to return to B_1 
at the last known scroll position. This is the code that I thought would 
do it--by remembering the former vertical adjustment and then setting it 
once the old content re-appears:

    webkit_web_view_load_string (WEBKIT_WEB_VIEW (B), htmlwriter.html.c_str(), NULL, NULL, NULL);
    // Scroll to the position that was stored while this url was last active.
    GtkAdjustment * adjustment = gtk_scrolled_window_get_vadjustment (GTK_SCROLLED_WINDOW (A));
    gtk_adjustment_set_value (adjustment, scrolling_position[active_url]);   <<=== This line doesn't do 
anything


scrolling_position[active_url] returns a value, say 1000, and the 
gtk_adjustment_set doesn't seem to have any effect.
Any pointers on how to fix this?
Thank you,
Matt