[gnome-music/wip/jfelder/new-playertoolbar: 12/14] playertoolbar: Center the button controls and the progress scale

[Jean Felder <jfelder src gnome org>]

commit f394a430b3b3e0d490a7b006863dacd4a18a7da3
Author: Jean Felder <jfelder src gnome org>
Date:   Thu Jan 28 16:51:18 2021 +0100

    playertoolbar: Center the button controls and the progress scale

 data/ui/PlayerToolbar.ui            | 7 +++++--
 gnomemusic/widgets/playertoolbar.py | 8 ++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)
---
diff --git a/data/ui/PlayerToolbar.ui b/data/ui/PlayerToolbar.ui
index e3f735cdf..8813affae 100644
--- a/data/ui/PlayerToolbar.ui
+++ b/data/ui/PlayerToolbar.ui
@@ -110,8 +110,8 @@
         </child>
       </object>
     </child>
-    <child>
-      <object class="GtkBox" id="buttons_and_scale">
+    <child type="center">
+      <object class="GtkBox" id="_buttons_and_scale">
         <property name="orientation">vertical</property>
         <property name="visible">True</property>
         <property name="can_focus">False</property>
@@ -260,6 +260,9 @@
           </object>
         </child>
       </object>
+      <packing>
+        <property name="pack-type">end</property>
+      </packing>
     </child>
   </template>
 </interface>
diff --git a/gnomemusic/widgets/playertoolbar.py b/gnomemusic/widgets/playertoolbar.py
index 87d7106a4..79171d4fd 100644
--- a/gnomemusic/widgets/playertoolbar.py
+++ b/gnomemusic/widgets/playertoolbar.py
@@ -44,6 +44,7 @@ class PlayerToolbar(Gtk.ActionBar):
 
     _artist_label = Gtk.Template.Child()
     _art_stack = Gtk.Template.Child()
+    _buttons_and_scale = Gtk.Template.Child()
     _duration_label = Gtk.Template.Child()
     _next_button = Gtk.Template.Child()
     _pause_image = Gtk.Template.Child()
@@ -72,6 +73,13 @@ class PlayerToolbar(Gtk.ActionBar):
 
         self._tooltip = TwoLineTip()
 
+        # A centered widget has an expand child property set to False
+        # by default. It needs to be True to have a progress scale
+        # at the correct size.
+        main_container = self._buttons_and_scale.get_parent()
+        main_container.child_set_property(
+            self._buttons_and_scale, "expand", True)
+
     # FIXME: This is a workaround for not being able to pass the player
     # object via init when using Gtk.Builder.
     @GObject.Property(type=Player, default=None)