- Add support for filtering by category

- Break up main window into partials instead of using regions

Application/MainWindow/CategoryList.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Linq;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace FeedCenter
+{
+    public partial class MainWindow
+    {
+        private void DisplayCategory()
+        {
+            CategoryLabel.Text = string.Format(Properties.Resources.CategoryFilterHeader, _currentCategory == null ? Properties.Resources.AllCategory : _currentCategory.Name);
+        }
+
+        private void HandleCategoryButtonClick(object sender, RoutedEventArgs e)
+        {
+            // Create a new context menu
+            var contextMenu = new ContextMenu();
+
+            // Create the "all" menu item
+            var menuItem = new MenuItem
+            {
+                Header = Properties.Resources.AllCategory,
+                Tag = null,
+
+                // Set the current item to bold
+                FontWeight = _currentCategory == null ? FontWeights.Bold : FontWeights.Normal
+            };
+
+            // Handle the click
+            menuItem.Click += HandleCategoryMenuItemClick;
+
+            // Add the item to the list
+            contextMenu.Items.Add(menuItem);
+
+            // Loop over each feed
+            foreach (var category in _database.Categories.OrderBy(category => category.Name))
+            {
+                // Create a menu item
+                menuItem = new MenuItem
+                {
+                    Header = category.Name,
+                    Tag = category,
+
+                    // Set the current item to bold
+                    FontWeight = category.ID == _currentCategory?.ID ? FontWeights.Bold : FontWeights.Normal
+                };
+
+                // Handle the click
+                menuItem.Click += HandleCategoryMenuItemClick;
+
+                // Add the item to the list
+                contextMenu.Items.Add(menuItem);
+            }
+
+            // Set the context menu placement to this button
+            contextMenu.PlacementTarget = this;
+
+            // Open the context menu
+            contextMenu.IsOpen = true;
+        }
+
+        private void HandleCategoryMenuItemClick(object sender, RoutedEventArgs e)
+        {
+            // Get the menu item clicked
+            var menuItem = (MenuItem) sender;
+
+            // Get the category from the menu item tab
+            var category = (Category) menuItem.Tag;
+
+            // If the category changed then reset the current feed to the first in the category
+            if (_currentCategory?.ID != category?.ID)
+            {
+                _currentFeed = category == null ? _database.Feeds.FirstOrDefault() : category.Feeds.FirstOrDefault();
+            }
+
+            // Set the current category
+            _currentCategory = category;
+
+            // Get the current feed list to match the category
+            _feedList = _currentCategory?.Feeds.ToList() ?? _database.Feeds.ToList();
+
+            // Reset the feed index
+            _feedIndex = -1;
+
+            // Get the first feed
+            NextFeed();
+
+            // Update the feed timestamp
+            _lastFeedDisplay = DateTime.Now;
+
+            // Update the display
+            DisplayCategory();
+            DisplayFeed();
+        }
+    }
+}