library: port Viewswitcher entry to Vala (#254)

Author: halfmexican

src/Library/demos/View Switcher/main.vala

@@ -0,0 +1,38 @@
+#! /usr/bin/env -S vala workbench.vala --pkg gtk4 --pkg libadwaita-1
+
+public void main() {
+  var notifications_page = workbench.builder.get_object("page3") as Adw.ViewStackPage;
+  var notification_list = workbench.builder.get_object("notification_list") as Gtk.ListBox;
+  
+  int notification_count = 5;
+  
+  notifications_page.badge_number = notification_count;
+  
+  for (int i = 0; i < notification_count; i++){
+    var notification_row = new Adw.ActionRow(){
+      title = "Notification",
+      selectable = false,
+    };
+    
+    var button = new Gtk.Button(){
+      halign = Gtk.Align.CENTER,
+      valign = Gtk.Align.CENTER,
+      margin_top = 10,
+      margin_bottom = 10,
+      icon_name = "check-plain-symbolic"
+    };
+    
+    button.clicked.connect( () => {
+      notifications_page.badge_number = --notification_count;
+      notification_list.remove(notification_row);
+      
+      if (notifications_page.badge_number == 0) 
+        notifications_page.needs_attention = false;
+    });
+    
+    notification_row.add_suffix(button);
+
+    notification_list.append(notification_row);
+  }
+}
+