[gtk+] placesview: Make middle click work

[Matthias Clasen <matthiasc src gnome org>]

commit 33fdcca2cf5c3f808e5d2567a89d6c059d36c65b
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Dec 12 13:56:15 2017 -0500

    placesview: Make middle click work
    
    This does not cost us much, and improves consistency.

 gtk/gtkplacesview.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkplacesview.c b/gtk/gtkplacesview.c
index c4bcb38..3281a09 100644
--- a/gtk/gtkplacesview.c
+++ b/gtk/gtkplacesview.c
@@ -1882,10 +1882,21 @@ on_listbox_row_activated (GtkPlacesView    *view,
                           GtkWidget        *listbox)
 {
   GtkPlacesViewPrivate *priv;
+  GdkEvent *event;
+  guint button;
+  GtkPlacesOpenFlags open_flags;
 
   priv = gtk_places_view_get_instance_private (view);
 
-  activate_row (view, row, priv->current_open_flags);
+  event = gtk_get_current_event ();
+  gdk_event_get_button (event, &button);
+
+  if (gdk_event_get_event_type (event) == GDK_BUTTON_RELEASE && button == GDK_BUTTON_MIDDLE)
+    open_flags = GTK_PLACES_OPEN_NEW_TAB;
+  else
+    open_flags = priv->current_open_flags;
+
+  activate_row (view, row, open_flags);
 }
 
 static gboolean