vbox.pack_start( label, FALSE, TRUE, 0 );
gtk_object_set_data( GTK_OBJECT( dlg ), "snap_text", label );
adj = ui::Adjustment( 8, 0, 256, 1, 10, 0 );
adj.connect( "value_changed", G_CALLBACK( extents_snaptogrid_spin ), &SP );
spin = ui::SpinButton( adj, 1, 0 );
vbox.pack_start( label, FALSE, TRUE, 0 );
gtk_object_set_data( GTK_OBJECT( dlg ), "snap_text", label );
adj = ui::Adjustment( 8, 0, 256, 1, 10, 0 );
adj.connect( "value_changed", G_CALLBACK( extents_snaptogrid_spin ), &SP );
spin = ui::SpinButton( adj, 1, 0 );