handle negative values similar to gtk_widget_set_uposition(). that is:

handle negative values similar to gtk_widget_set_uposition(). that is:

Thu Jul 16 01:27:15 1998  Tim Janik  <timj@gtk.org>

        * gtk/gtkwidget.h:
        * gtk/gtkwidget.c (gtk_widget_set_usize): handle negative values
        similar to gtk_widget_set_uposition(). that is: -1=unspecified,
        -2=leave untouched. changed the width/height field of GtkWidgetAuxInfo
        to be gint16s rather than guint16s, since that's what the code expected
        (for a long time actually).

        * gtk/gtkviewport.c:
        added support for object arguments: GtkViewport::shadow_type,
        GtkViewport::vadjustment and GtkViewport::hadjustment.
        (gtk_viewport_add): chain gtk_bin_add.

        * gtk/gtkscrolledwindow.c:
        added support for object argument: GtkScrolledWindow::hscrollbar_policy,
        GtkScrolledWindow::vscrollbar_policy and GtkScrolledWindow::viewport.

        * gtk/gtkadjustment.h:
        * gtk/gtkadjustment.c:
        * gtk/gtkctree.h:
        * gtk/gtkclist.h:
        * gtk/gtkctree.c:
        * gtk/gtkclist.c:
        * gtk/gtkscrolledwindow.h:
        * gtk/gtkscrolledwindow.c:
        * gtk/gtkviewport.h:
        * gtk/gtkviewport.c:
        GtkType and macro fixups.