ShowWidget: Retain vertical scrolling adjustment upon view refresh.

hammond-gtk/resources/gtk/show_widget.ui

@@ -7,7 +7,8 @@
     <property name="can_focus">False</property>
     <property name="orientation">vertical</property>
     <child>
-      <object class="GtkScrolledWindow">
+      <object class="GtkScrolledWindow" id="scrolled_window">
+        <property name="name">scrolled_window</property>
         <property name="visible">True</property>
         <property name="can_focus">True</property>
         <property name="shadow_type">in</property>

hammond-gtk/src/content.rs

@@ -1,4 +1,5 @@
 use gtk;
+use gtk::Cast;
 use gtk::prelude::*;
 
 use hammond_data::Podcast;
@@ -129,8 +130,30 @@ impl ShowStack {
     }
 
     pub fn replace_widget(&self, pd: &Podcast) {
-        let old = self.stack.get_child_by_name("widget").unwrap();
+        let old = self.stack
+            .get_child_by_name("widget")
+            // This is guaranted to exists, based on ShowStack::new().
+            .unwrap()
+            .downcast::<gtk::Box>()
+            // This is guaranted to be a Box based on the ShowWidget impl.
+            .unwrap();
+        debug!("Name: {:?}", WidgetExt::get_name(&old));
+
+        let scrolled_window = old.get_children()
+            .first()
+            // This is guaranted to exist based on the show_widget.ui file.
+            .unwrap()
+            .clone()
+            .downcast::<gtk::ScrolledWindow>()
+            // This is guaranted based on the show_widget.ui file.
+            .unwrap();
+        debug!("Name: {:?}", WidgetExt::get_name(&scrolled_window));
+
         let new = ShowWidget::new(Arc::new(self.clone()), pd, self.sender.clone());
+        // Copy the vertical scrollbar adjustment from the old view into the new one.
+        scrolled_window
+            .get_vadjustment()
+            .map(|x| new.set_vadjustment(&x));
 
         self.stack.remove(&old);
         self.stack.add_named(&new.container, "widget");
@@ -193,24 +216,27 @@ impl EpisodeStack {
     }
 
     pub fn update(&self) {
-        use gtk::Cast;
-
         let old = self.stack
             .get_child_by_name("episodes")
+            // This is guaranted to exists, based on EpisodeStack::new().
             .unwrap()
             .downcast::<gtk::Box>()
+            // This is guaranted to be a Box based on the EpisodesView impl.
             .unwrap();
-        info!("Name: {:?}", WidgetExt::get_name(&old));
+        debug!("Name: {:?}", WidgetExt::get_name(&old));
 
         let scrolled_window = old.get_children()
             .first()
+            // This is guaranted to exist based on the episodes_view.ui file.
             .unwrap()
             .clone()
             .downcast::<gtk::ScrolledWindow>()
+            // This is guaranted based on the episodes_view.ui file.
             .unwrap();
-        info!("Name: {:?}", WidgetExt::get_name(&scrolled_window));
+        debug!("Name: {:?}", WidgetExt::get_name(&scrolled_window));
 
         let eps = EpisodesView::new(self.sender.clone());
+        // Copy the vertical scrollbar adjustment from the old view into the new one.
         scrolled_window
             .get_vadjustment()
             .map(|x| eps.set_vadjustment(&x));

hammond-gtk/src/views/episodes.rs

@@ -151,6 +151,7 @@ impl EpisodesView {
         true
     }
 
+    /// Set scrolled window vertical adjustment.
     pub fn set_vadjustment(&self, vadjustment: &gtk::Adjustment) {
         self.scrolled_window.set_vadjustment(vadjustment)
     }

hammond-gtk/src/widgets/show.rs

@@ -21,6 +21,7 @@ use std::fs;
 #[derive(Debug, Clone)]
 pub struct ShowWidget {
     pub container: gtk::Box,
+    scrolled_window: gtk::ScrolledWindow,
     cover: gtk::Image,
     description: gtk::Label,
     link: gtk::Button,
@@ -33,6 +34,7 @@ impl Default for ShowWidget {
     fn default() -> Self {
         let builder = gtk::Builder::new_from_resource("/org/gnome/hammond/gtk/show_widget.ui");
         let container: gtk::Box = builder.get_object("container").unwrap();
+        let scrolled_window: gtk::ScrolledWindow = builder.get_object("scrolled_window").unwrap();
         let episodes: gtk::Frame = builder.get_object("episodes").unwrap();
 
         let cover: gtk::Image = builder.get_object("cover").unwrap();
@@ -43,6 +45,7 @@ impl Default for ShowWidget {
 
         ShowWidget {
             container,
+            scrolled_window,
             cover,
             description,
             unsub,
@@ -104,6 +107,11 @@ impl ShowWidget {
         let desc = dissolve::strip_html_tags(text).join(" ");
         self.description.set_text(&replace_extra_spaces(&desc));
     }
+
+    /// Set scrolled window vertical adjustment.
+    pub fn set_vadjustment(&self, vadjustment: &gtk::Adjustment) {
+        self.scrolled_window.set_vadjustment(vadjustment)
+    }
 }
 
 fn on_unsub_button_clicked(