[gtkmm-documentation] pack_start/end() calls: Specify EXPAND_WIDGET explicitly.

[Murray Cumming <murrayc src gnome org>]

commit fb6a06648093c29bf0465885da250f0c9ecc5b5f
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed May 3 17:57:13 2017 +0200

    pack_start/end() calls: Specify EXPAND_WIDGET explicitly.
    
    These are intendend to call the pack_start(child, options) method,
    using the default options value of EXPAND_WIDGET, but would now
    call the pack_start(child) method unless we specify the value
    explicitly.

 examples/book/placessidebar/examplewindow.cc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/examples/book/placessidebar/examplewindow.cc b/examples/book/placessidebar/examplewindow.cc
index cc3a154..cbc0a33 100644
--- a/examples/book/placessidebar/examplewindow.cc
+++ b/examples/book/placessidebar/examplewindow.cc
@@ -132,7 +132,7 @@ void ExampleWindow::on_placessidebar_populate_popup(Gtk::Container* container, c
     properties_button->signal_clicked().connect(sigc::mem_fun(*this, 
&ExampleWindow::on_menu_properties_activate));
     properties_button->show();
 
-    box->pack_end(*properties_button);
+    box->pack_end(*properties_button, Gtk::PackOptions::EXPAND_WIDGET);
   }
   else
   {