[gitg] sidebar: fixes for new gtk to avoid style context warnings

[Ignacio Casal Quinteiro <icq src gnome org>]

commit c1c862b907d0f5c18031c9593079b672c6779b32
Author: Ignacio Casal Quinteiro <icq gnome org>
Date:   Mon Dec 21 09:30:46 2015 +0100

    sidebar: fixes for new gtk to avoid style context warnings

 libgitg/gitg-sidebar.vala |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/libgitg/gitg-sidebar.vala b/libgitg/gitg-sidebar.vala
index 36aa66a..43fa9c8 100644
--- a/libgitg/gitg-sidebar.vala
+++ b/libgitg/gitg-sidebar.vala
@@ -251,7 +251,13 @@ public class Sidebar : Gtk.TreeView
 
                        if (hint == SidebarHint.DUMMY)
                        {
-                               var col = get_style_context().get_color(Gtk.StateFlags.INSENSITIVE);
+                               var context = get_style_context();
+
+                               context.save();
+                               context.set_state(Gtk.StateFlags.INSENSITIVE);
+                               var col = context.get_color(context.get_state());
+                               context.restore();
+
                                r.foreground_rgba = col;
                        }
                        else