[gnome-control-center] sound: Embed the "Applications" tab content in a scrolled window

[Felipe Borges <felipeborges src gnome org>]

commit b3d51d905128d83eb8df7cb59a58daf841acda34
Author: Felipe Borges <felipeborges gnome org>
Date:   Thu Jan 4 15:28:06 2018 +0100

    sound: Embed the "Applications" tab content in a scrolled window
    
    The "Applications" tab might expand vertically indefinitely depending
    on the amount of applications playing sounds simultaneously. This
    causes the whole Control Center window to grow vertically.
    
    To reproduce the issue you'd need to launch multiple sound sources.
      1. Launch "gst-play-1.0 <music file>"
      2. Press space to pause the playback
      3. Press Ctrl+Z to send it into the background
      4. Goto 1.
    
    These changes pack the content of the "Applications" tab in a
    GtkScrolledWindow.
    
    To avoid having the scrollbar overlapping the switchers, we set a
    10px margin-end to the inner container.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786684

 panels/sound/gvc-mixer-dialog.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/panels/sound/gvc-mixer-dialog.c b/panels/sound/gvc-mixer-dialog.c
index 6f254cf..1f35d13 100644
--- a/panels/sound/gvc-mixer-dialog.c
+++ b/panels/sound/gvc-mixer-dialog.c
@@ -1784,9 +1784,13 @@ gvc_mixer_dialog_constructor (GType                  type,
         /* Applications */
         self->applications_box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
         gtk_container_set_border_width (GTK_CONTAINER (self->applications_box), 12);
+        gtk_widget_set_margin_end (self->applications_box, 10);
         label = gtk_label_new (_("Applications"));
+
+        box = gtk_scrolled_window_new (NULL, NULL);
+        gtk_container_add (GTK_CONTAINER (box), self->applications_box);
         gtk_notebook_append_page (GTK_NOTEBOOK (self->notebook),
-                                  self->applications_box,
+                                  box,
                                   label);
         self->no_apps_label = gtk_label_new (_("No application is currently playing or recording audio."));
         gtk_box_pack_start (GTK_BOX (self->applications_box),