More cleanup and fixes

Application/Data/LegacyDatabase.cs

@@ -185,6 +185,9 @@ public static class LegacyDatabase
         {
             foreach (var category in categories)
             {
+                if (category.Name == Category.DefaultName)
+                    category.IsDefault = true;
+
                 category.Feeds = feeds.Where(f => f.CategoryId == category.Id).ToList();
             }
 

Application/Data/RealmObservableCollection.cs

@@ -26,4 +26,4 @@ namespace FeedCenter.Data
             base.OnCollectionChanged(e);
         }
     }
-}
+}

Application/Entities.cs

@@ -8,9 +8,9 @@ namespace FeedCenter
 {
     public class FeedCenterEntities
     {
-        public Realm Realm { get; private set; }
+        public Realm RealmInstance { get; }
 
-        public RealmObservableCollection<Category> Categories { get; private set; }
+        public RealmObservableCollection<Category> Categories { get; }
         public RealmObservableCollection<Feed> Feeds { get; private set; }
         public RealmObservableCollection<Setting> Settings { get; private set; }
 
@@ -18,26 +18,31 @@ namespace FeedCenter
         {
             var realmConfiguration = new RealmConfiguration($"{Database.DatabaseFile}");
 
-            Realm = Realm.GetInstance(realmConfiguration);
+            RealmInstance = Realm.GetInstance(realmConfiguration);
 
-            Settings = new RealmObservableCollection<Setting>(Realm);
+            Settings = new RealmObservableCollection<Setting>(RealmInstance);
-            Feeds = new RealmObservableCollection<Feed>(Realm);
+            Feeds = new RealmObservableCollection<Feed>(RealmInstance);
-            Categories = new RealmObservableCollection<Category>(Realm);
+            Categories = new RealmObservableCollection<Category>(RealmInstance);
 
             if (!Categories.Any())
             {
-                Realm.Write(() => Categories.Add(Category.CreateDefault()));
+                RealmInstance.Write(() => Categories.Add(Category.CreateDefault()));
             }
         }
 
         public void Refresh()
         {
-            Realm.Refresh();
+            RealmInstance.Refresh();
         }
 
         public void SaveChanges(Action action)
         {
-            Realm.Write(action);
+            RealmInstance.Write(action);
+        }
+
+        public Transaction BeginTransaction()
+        {
+            return RealmInstance.BeginWrite();
         }
 
         public Category DefaultCategory

Application/FeedErrorWindow.xaml.cs

@@ -65,7 +65,7 @@ namespace FeedCenter
 
             var feedWindow = new FeedWindow();
 
-            feedWindow.Display(_database, feed, GetWindow(this));
+            feedWindow.Display(feed, GetWindow(this));
         }
 
         private void DeleteSelectedFeed()

Application/Feeds/Category.cs

@@ -1,33 +1,90 @@
 using Realms;
 using System;
+using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
 
 namespace FeedCenter
 {
-    public class Category : RealmObject
+    public class Category : RealmObject, INotifyDataErrorInfo
     {
-        private const string DefaultCategoryName = "< default >";
+        public const string DefaultName = "< default >";
+
+        private readonly Dictionary<string, List<string>> _errorsByPropertyName = new();
 
         [PrimaryKey]
-        [MapTo("ID")]
+        public Guid Id { get; set; } = Guid.NewGuid();
-        public Guid Id { get; set; }
+
-        public string Name { get; set; }
+        [MapTo("Name")]
+        private string RawName { get; set; } = string.Empty;
+
+        public string Name
+        {
+            get => RawName;
+            set
+            {
+                RawName = value;
+
+                ValidateName();
+                RaisePropertyChanged();
+            }
+        }
 
         [Ignored]
         public ICollection<Feed> Feeds { get; set; }
 
-        public static Category Create()
-        {
-            return new Category { Id = Guid.NewGuid() };
-        }
         public static Category CreateDefault()
         {
-            return new Category { Id = Guid.NewGuid(), Name = DefaultCategoryName };
+            return new Category { Name = DefaultName, IsDefault = true };
         }
 
-        public bool IsDefault => Name == DefaultCategoryName;
+        public bool IsDefault { get; internal set; }
 
         // ReSharper disable once UnusedMember.Global
         public int SortKey => IsDefault ? 0 : 1;
+
+        public bool HasErrors => _errorsByPropertyName.Any();
+
+        public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
+
+        public IEnumerable GetErrors(string propertyName)
+        {
+            return _errorsByPropertyName.TryGetValue(propertyName, out var value) ? value : null;
+        }
+
+        private void OnErrorsChanged(string propertyName)
+        {
+            ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
+        }
+
+        private void ValidateName()
+        {
+            ClearErrors(nameof(Name));
+
+            if (string.IsNullOrWhiteSpace(Name))
+                AddError(nameof(Name), "Name cannot be empty");
+        }
+
+        private void AddError(string propertyName, string error)
+        {
+            if (!_errorsByPropertyName.ContainsKey(propertyName))
+                _errorsByPropertyName[propertyName] = new List<string>();
+
+            if (_errorsByPropertyName[propertyName].Contains(error))
+                return;
+
+            _errorsByPropertyName[propertyName].Add(error);
+            OnErrorsChanged(propertyName);
+        }
+
+        private void ClearErrors(string propertyName)
+        {
+            if (!_errorsByPropertyName.ContainsKey(propertyName))
+                return;
+
+            _errorsByPropertyName.Remove(propertyName);
+            OnErrorsChanged(propertyName);
+        }
     }
-}
+}

Application/Feeds/Feed.cs

@@ -1,4 +1,5 @@
 using ChrisKaczor.ApplicationUpdate;
+using FeedCenter.Data;
 using FeedCenter.FeedParsers;
 using FeedCenter.Properties;
 using FeedCenter.Xml;
@@ -118,9 +119,9 @@ namespace FeedCenter
 
         private static HttpClient _httpClient;
 
-        public static Feed Create(FeedCenterEntities database)
+        public static Feed Create()
         {
-            return new Feed { Id = Guid.NewGuid(), CategoryId = database.DefaultCategory.Id };
+            return new Feed { Id = Guid.NewGuid(), CategoryId = Database.Entities.DefaultCategory.Id };
         }
 
         #region Reading

Application/MainWindow/FeedCreation.cs

@@ -20,7 +20,7 @@ namespace FeedCenter
         private void HandleNewFeed(string feedUrl)
         {
             // Create and configure the new feed
-            var feed = Feed.Create(_database);
+            var feed = Feed.Create();
             feed.Source = feedUrl;
             feed.Category = _database.DefaultCategory;
 
@@ -85,7 +85,7 @@ namespace FeedCenter
                 // Feed read failed - create a new feed window
                 var feedForm = new FeedWindow();
 
-                var dialogResult = feedForm.Display(_database, feed, this);
+                var dialogResult = feedForm.Display(feed, this);
 
                 // Display the new feed form
                 if (dialogResult.HasValue && dialogResult.Value)

Application/MainWindow/Toolbar.cs

@@ -145,7 +145,7 @@ namespace FeedCenter
             var feedWindow = new FeedWindow();
 
             // Display the feed window and get the result
-            var result = feedWindow.Display(_database, _currentFeed, this);
+            var result = feedWindow.Display(_currentFeed, this);
 
             // If OK was clicked...
             if (result.HasValue && result.Value)

Application/Options/AboutOptionsPanel.xaml.cs

@@ -1,36 +1,26 @@
 using ChrisKaczor.ApplicationUpdate;
 using System.Reflection;
 
-namespace FeedCenter.Options
+namespace FeedCenter.Options;
+
+public partial class AboutOptionsPanel
 {
-    public partial class AboutOptionsPanel
+    public AboutOptionsPanel()
     {
-        public AboutOptionsPanel()
+        InitializeComponent();
-        {
-            InitializeComponent();
-        }
-
-        public override void LoadPanel(FeedCenterEntities database)
-        {
-            base.LoadPanel(database);
-
-            ApplicationNameLabel.Text = Properties.Resources.ApplicationDisplayName;
-
-            var version = UpdateCheck.LocalVersion.ToString();
-            VersionLabel.Text = string.Format(Properties.Resources.Version, version);
-
-            CompanyLabel.Text = ((AssemblyCompanyAttribute) Assembly.GetEntryAssembly().GetCustomAttributes(typeof(AssemblyCompanyAttribute), false)[0]).Company;
-        }
-
-        public override bool ValidatePanel()
-        {
-            return true;
-        }
-
-        public override void SavePanel()
-        {
-        }
-
-        public override string CategoryName => Properties.Resources.optionCategoryAbout;
     }
+
+    public override void LoadPanel()
+    {
+        base.LoadPanel();
+
+        ApplicationNameLabel.Text = Properties.Resources.ApplicationDisplayName;
+
+        var version = UpdateCheck.LocalVersion.ToString();
+        VersionLabel.Text = string.Format(Properties.Resources.Version, version);
+
+        CompanyLabel.Text = ((AssemblyCompanyAttribute) Assembly.GetEntryAssembly().GetCustomAttributes(typeof(AssemblyCompanyAttribute), false)[0]).Company;
+    }
+
+    public override string CategoryName => Properties.Resources.optionCategoryAbout;
 }

Application/Options/BulkFeedWindow.xaml.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
+using FeedCenter.Data;
 
 namespace FeedCenter.Options
 {
@@ -17,11 +18,11 @@ namespace FeedCenter.Options
             InitializeComponent();
         }
 
-        public void Display(Window window, FeedCenterEntities database)
+        public void Display(Window window)
         {
             _checkedListBoxItems = new List<CheckedListItem<Feed>>();
 
-            foreach (var feed in database.Feeds)
+            foreach (var feed in Database.Entities.Feeds)
                 _checkedListBoxItems.Add(new CheckedListItem<Feed> { Item = feed });
 
             _collectionViewSource = new CollectionViewSource { Source = _checkedListBoxItems };

Application/Options/CategoryWindow.xaml

@@ -6,7 +6,6 @@
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         mc:Ignorable="d"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-        xmlns:validation="clr-namespace:ChrisKaczor.Wpf.Validation;assembly=ChrisKaczor.Wpf.Validation"
         xmlns:controls="clr-namespace:ChrisKaczor.Wpf.Windows;assembly=ChrisKaczor.Wpf.Windows.ControlBox"
         d:DataContext="{d:DesignInstance Type=feedCenter:Category}"
         Title="CategoryWindow"
@@ -18,40 +17,31 @@
         FocusManager.FocusedElement="{Binding ElementName=NameTextBox}"
         controls:ControlBox.HasMinimizeButton="False"
         controls:ControlBox.HasMaximizeButton="False">
-    <Grid Margin="8">
+    <Grid Margin="6,3,6,6">
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto" />
             <RowDefinition Height="*" />
-            <RowDefinition Height="Auto" />
         </Grid.RowDefinitions>
         <Grid.ColumnDefinitions>
-            <ColumnDefinition Width="Auto" />
             <ColumnDefinition Width="*" />
         </Grid.ColumnDefinitions>
-        <Label Content="{x:Static properties:Resources.feedCategoryLabel}"
+        <StackPanel 
-               HorizontalAlignment="Left"
+            Grid.Row="0" 
-               Grid.Column="0" 
+            Grid.Column="0">
-               Grid.Row="0"
+            <Label Content="{x:Static properties:Resources.categoryNameLabel}"
-               Target="{Binding ElementName=NameTextBox}"
+                   Padding="0"
-               VerticalAlignment="Center"
+                   Margin="0,0,0,1"
-               VerticalContentAlignment="Center" />
+                   Target="{Binding ElementName=NameTextBox}" />
-        <TextBox Name="NameTextBox"
+            <TextBox Name="NameTextBox"
-                 VerticalAlignment="Center"
+                     VerticalAlignment="Center"
-                 Grid.Row="0"
+                     Text="{Binding Path=Name, UpdateSourceTrigger=PropertyChanged, ValidatesOnExceptions=True}">
-                 Grid.Column="1">
+            </TextBox>
-            <TextBox.Text>
+        </StackPanel>
-                <Binding Path="Name" UpdateSourceTrigger="Explicit" ValidatesOnExceptions="True">
-                    <Binding.ValidationRules>
-                        <validation:RequiredValidationRule></validation:RequiredValidationRule>
-                    </Binding.ValidationRules>
-                </Binding>
-            </TextBox.Text>
-        </TextBox>
         <StackPanel
-            Grid.Column="1"
+            Grid.Column="0"
-            Grid.Row="2"
+            Grid.Row="1"
             Orientation="Horizontal"
-            Margin="0,4,0,0"
+            Margin="0,5,0,0"
             HorizontalAlignment="Right">
             <Button Content="{x:Static properties:Resources.OkayButton}"
                     Height="23"

Application/Options/CategoryWindow.xaml.cs

@@ -1,5 +1,6 @@
 using ChrisKaczor.Wpf.Validation;
 using System.Windows;
+using FeedCenter.Data;
 
 namespace FeedCenter.Options
 {
@@ -29,8 +30,16 @@ namespace FeedCenter.Options
 
         private void HandleOkayButtonClick(object sender, RoutedEventArgs e)
         {
+            var transaction = Database.Entities.BeginTransaction();
+
             if (!this.IsValid())
+            {
+                transaction.Rollback();
                 return;
+            }
+
+            transaction.Commit();
+            Database.Entities.Refresh();
 
             // Dialog is good
             DialogResult = true;

Application/Options/DisplayOptionsPanel.xaml

@@ -19,7 +19,8 @@
                   Name="LockWindowCheckBox"
                   VerticalAlignment="Top"
                   Width="300"
-                  Grid.ColumnSpan="2" />
+                  Grid.ColumnSpan="2"
+                  Click="LockWindowCheckBox_Click" />
         <CheckBox Content="{x:Static properties:Resources.displayEmptyFeedsCheckBox}"
                   Height="16"
                   HorizontalAlignment="Left"
@@ -28,7 +29,8 @@
                   VerticalAlignment="Top"
                   Width="300"
                   Grid.ColumnSpan="2"
-                  Grid.Column="0" />
+                  Grid.Column="0"
+                  Click="DisplayEmptyFeedsCheckBox_Click" />
         <Label Grid.Column="0"
                Content="{x:Static properties:Resources.toolbarLocationLabel}"
                VerticalAlignment="Top"
@@ -39,7 +41,8 @@
         <ComboBox Margin="8,53,0,0"
                   Name="ToolbarLocationComboBox"
                   VerticalAlignment="Top"
-                  Grid.Column="1">
+                  Grid.Column="1"
+                  SelectionChanged="ToolbarLocationComboBox_SelectionChanged">
             <ComboBoxItem Content="{x:Static properties:Resources.Top}"
                           Tag="{x:Static Dock.Top}" />
             <ComboBoxItem Content="{x:Static properties:Resources.Bottom}"
@@ -55,7 +58,8 @@
         <ComboBox Margin="8,86,0,0"
                   Name="MultipleLineDisplayComboBox"
                   VerticalAlignment="Top"
-                  Grid.Column="1">
+                  Grid.Column="1"
+                  SelectionChanged="MultipleLineDisplayComboBox_SelectionChanged">
             <ComboBoxItem Content="{x:Static properties:Resources.multipleLineDisplayNormal}"
                           Tag="{x:Static options:MultipleLineDisplay.Normal}" />
             <ComboBoxItem Content="{x:Static properties:Resources.multipleLineDisplaySingleLine}"
@@ -64,4 +68,4 @@
                           Tag="{x:Static options:MultipleLineDisplay.FirstLine}" />
         </ComboBox>
     </Grid>
-</options:OptionsPanelBase>
+</options:OptionsPanelBase>

Application/Options/DisplayOptionsPanel.xaml.cs

@@ -2,45 +2,58 @@
 using System.Linq;
 using System.Windows.Controls;
 
-namespace FeedCenter.Options
+namespace FeedCenter.Options;
+
+public partial class DisplayOptionsPanel
 {
-    public partial class DisplayOptionsPanel
+    public DisplayOptionsPanel()
     {
-        public DisplayOptionsPanel()
+        InitializeComponent();
-        {
-            InitializeComponent();
-        }
-
-        public override void LoadPanel(FeedCenterEntities database)
-        {
-            base.LoadPanel(database);
-
-            LockWindowCheckBox.IsChecked = Settings.Default.WindowLocked;
-            DisplayEmptyFeedsCheckBox.IsChecked = Settings.Default.DisplayEmptyFeeds;
-            ToolbarLocationComboBox.SelectedItem = ToolbarLocationComboBox.Items.Cast<ComboBoxItem>().First(comboBoxItem => (Dock) comboBoxItem.Tag == Settings.Default.ToolbarLocation);
-            MultipleLineDisplayComboBox.SelectedItem = MultipleLineDisplayComboBox.Items.Cast<ComboBoxItem>().First(comboBoxItem => (MultipleLineDisplay) comboBoxItem.Tag == Settings.Default.MultipleLineDisplay);
-        }
-
-        public override bool ValidatePanel()
-        {
-            return true;
-        }
-
-        public override void SavePanel()
-        {
-            if (LockWindowCheckBox.IsChecked.HasValue && Settings.Default.WindowLocked != LockWindowCheckBox.IsChecked.Value)
-                Settings.Default.WindowLocked = LockWindowCheckBox.IsChecked.Value;
-
-            if (DisplayEmptyFeedsCheckBox.IsChecked.HasValue && Settings.Default.DisplayEmptyFeeds != DisplayEmptyFeedsCheckBox.IsChecked.Value)
-                Settings.Default.DisplayEmptyFeeds = DisplayEmptyFeedsCheckBox.IsChecked.Value;
-
-            var dock = (Dock) ((ComboBoxItem) ToolbarLocationComboBox.SelectedItem).Tag;
-            Settings.Default.ToolbarLocation = dock;
-
-            var multipleLineDisplay = (MultipleLineDisplay) ((ComboBoxItem) MultipleLineDisplayComboBox.SelectedItem).Tag;
-            Settings.Default.MultipleLineDisplay = multipleLineDisplay;
-        }
-
-        public override string CategoryName => Properties.Resources.optionCategoryDisplay;
     }
-}
+
+    public override void LoadPanel()
+    {
+        base.LoadPanel();
+
+        LockWindowCheckBox.IsChecked = Settings.Default.WindowLocked;
+        DisplayEmptyFeedsCheckBox.IsChecked = Settings.Default.DisplayEmptyFeeds;
+        ToolbarLocationComboBox.SelectedItem = ToolbarLocationComboBox.Items.Cast<ComboBoxItem>().First(comboBoxItem => (Dock) comboBoxItem.Tag == Settings.Default.ToolbarLocation);
+        MultipleLineDisplayComboBox.SelectedItem = MultipleLineDisplayComboBox.Items.Cast<ComboBoxItem>().First(comboBoxItem => (MultipleLineDisplay) comboBoxItem.Tag == Settings.Default.MultipleLineDisplay);
+
+        MarkLoaded();
+    }
+
+    public override string CategoryName => Properties.Resources.optionCategoryDisplay;
+
+    private void LockWindowCheckBox_Click(object sender, System.Windows.RoutedEventArgs e)
+    {
+        if (!HasLoaded) return;
+
+        if (LockWindowCheckBox.IsChecked.HasValue && Settings.Default.WindowLocked != LockWindowCheckBox.IsChecked.Value)
+            Settings.Default.WindowLocked = LockWindowCheckBox.IsChecked.Value;
+    }
+
+    private void DisplayEmptyFeedsCheckBox_Click(object sender, System.Windows.RoutedEventArgs e)
+    {
+        if (!HasLoaded) return;
+
+        if (DisplayEmptyFeedsCheckBox.IsChecked.HasValue && Settings.Default.DisplayEmptyFeeds != DisplayEmptyFeedsCheckBox.IsChecked.Value)
+            Settings.Default.DisplayEmptyFeeds = DisplayEmptyFeedsCheckBox.IsChecked.Value;
+    }
+
+    private void ToolbarLocationComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (!HasLoaded) return;
+
+        var dock = (Dock) ((ComboBoxItem) ToolbarLocationComboBox.SelectedItem).Tag;
+        Settings.Default.ToolbarLocation = dock;
+    }
+
+    private void MultipleLineDisplayComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (!HasLoaded) return;
+
+        var multipleLineDisplay = (MultipleLineDisplay) ((ComboBoxItem) MultipleLineDisplayComboBox.SelectedItem).Tag;
+        Settings.Default.MultipleLineDisplay = multipleLineDisplay;
+    }
+}

Application/Options/FeedWindow.xaml.cs

@@ -1,4 +1,5 @@
 using ChrisKaczor.Wpf.Validation;
+using FeedCenter.Data;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -14,10 +15,10 @@ namespace FeedCenter.Options
             InitializeComponent();
         }
 
-        public bool? Display(FeedCenterEntities database, Feed feed, Window owner)
+        public bool? Display(Feed feed, Window owner)
         {
             // Bind the category combo box
-            CategoryComboBox.ItemsSource = database.Categories;
+            CategoryComboBox.ItemsSource = Database.Entities.Categories;
 
             // Set the data context
             DataContext = feed;
@@ -85,4 +86,4 @@ namespace FeedCenter.Options
             Close();
         }
     }
-}
+}

Application/Options/FeedsOptionsPanel.xaml

@@ -6,6 +6,7 @@
                           xmlns:options="clr-namespace:FeedCenter.Options"
                           xmlns:properties="clr-namespace:FeedCenter.Properties"
                           xmlns:controls="clr-namespace:ChrisKaczor.Wpf.Controls;assembly=ChrisKaczor.Wpf.Controls.Link"
+                          xmlns:feedCenter="clr-namespace:FeedCenter"
                           mc:Ignorable="d"
                           d:DesignHeight="311"
                           d:DesignWidth="425">
@@ -65,7 +66,8 @@
                   IsReadOnly="True"
                   HeadersVisibility="Column"
                   AllowDrop="True"
-                  Background="{x:Null}">
+                  Background="{x:Null}" 
+                  d:DataContext="{d:DesignInstance Type=feedCenter:Category }">
             <DataGrid.Columns>
                 <DataGridTextColumn Binding="{Binding Name}"
                                     Header="{x:Static properties:Resources.CategoryNameColumnHeader}"
@@ -75,11 +77,13 @@
             <DataGrid.ItemContainerStyle>
                 <Style TargetType="DataGridRow">
                     <EventSetter Event="Drop"
-                                 Handler="HandleTextBlockDrop" />
+                                 Handler="CategoryListBox_Drop" />
                     <EventSetter Event="DragEnter"
-                                 Handler="HandleTextBlockDragEnter" />
+                                 Handler="CategoryListBox_DragEnter" />
                     <EventSetter Event="DragLeave"
-                                 Handler="HandleTextBlockDragLeave" />
+                                 Handler="CategoryListBox_DragLeave" />
+                    <EventSetter Event="MouseDoubleClick"
+                                 Handler="CategoryListBox_MouseDoubleClick" />
                 </Style>
             </DataGrid.ItemContainerStyle>
             <DataGrid.CellStyle>

Application/Options/FeedsOptionsPanel.xaml.cs

@@ -7,58 +7,42 @@ using System.Windows.Controls;
 using System.Windows.Data;
 using System.Windows.Input;
 using System.Xml;
+using FeedCenter.Data;
 
 namespace FeedCenter.Options
 {
     public partial class FeedsOptionsPanel
     {
-        #region Constructor
-
         public FeedsOptionsPanel()
         {
             InitializeComponent();
         }
 
-        #endregion
+        public override void LoadPanel()
-
-        #region OptionsPanelBase overrides
-
-        public override void LoadPanel(FeedCenterEntities database)
         {
-            base.LoadPanel(database);
+            base.LoadPanel();
 
-            var collectionViewSource = new CollectionViewSource { Source = Database.Categories };
+            var collectionViewSource = new CollectionViewSource { Source = Database.Entities.Categories };
             collectionViewSource.SortDescriptions.Add(new SortDescription("SortKey", ListSortDirection.Ascending));
             collectionViewSource.SortDescriptions.Add(new SortDescription("Name", ListSortDirection.Ascending));
+            collectionViewSource.IsLiveSortingRequested = true;
 
             CategoryListBox.ItemsSource = collectionViewSource.View;
             CategoryListBox.SelectedIndex = 0;
         }
 
-        public override bool ValidatePanel()
-        {
-            return true;
-        }
-
-        public override void SavePanel()
-        { }
-
         public override string CategoryName => Properties.Resources.optionCategoryFeeds;
 
-        #endregion
-
-        #region Feed list management
-
         private void SetFeedButtonStates()
         {
             AddFeedButton.IsEnabled = true;
-            EditFeedButton.IsEnabled = (FeedListBox.SelectedItem != null);
+            EditFeedButton.IsEnabled = FeedListBox.SelectedItem != null;
-            DeleteFeedButton.IsEnabled = (FeedListBox.SelectedItem != null);
+            DeleteFeedButton.IsEnabled = FeedListBox.SelectedItem != null;
         }
 
         private void AddFeed()
         {
-            var feed = Feed.Create(Database);
+            var feed = Feed.Create();
 
             var category = (Category) CategoryListBox.SelectedItem;
 
@@ -66,16 +50,16 @@ namespace FeedCenter.Options
 
             var feedWindow = new FeedWindow();
 
-            var result = feedWindow.Display(Database, feed, Window.GetWindow(this));
+            var result = feedWindow.Display(feed, Window.GetWindow(this));
 
-            if (result.HasValue && result.Value)
+            if (!result.HasValue || !result.Value) 
-            {
+                return;
-                Database.Feeds.Add(feed);
 
-                FeedListBox.SelectedItem = feed;
+            Database.Entities.Feeds.Add(feed);
 
-                SetFeedButtonStates();
+            FeedListBox.SelectedItem = feed;
-            }
+
+            SetFeedButtonStates();
         }
 
         private void EditSelectedFeed()
@@ -87,22 +71,18 @@ namespace FeedCenter.Options
 
             var feedWindow = new FeedWindow();
 
-            feedWindow.Display(Database, feed, Window.GetWindow(this));
+            feedWindow.Display(feed, Window.GetWindow(this));
         }
 
         private void DeleteSelectedFeed()
         {
             var feed = (Feed) FeedListBox.SelectedItem;
 
-            Database.Feeds.Remove(feed);
+            Database.Entities.Feeds.Remove(feed);
 
             SetFeedButtonStates();
         }
 
-        #endregion
-
-        #region Feed event handlers
-
         private void HandleAddFeedButtonClick(object sender, RoutedEventArgs e)
         {
             AddFeed();
@@ -128,15 +108,11 @@ namespace FeedCenter.Options
             ExportFeeds();
         }
 
-        #endregion
+        private static void ExportFeeds()
-
-        #region Feed import and export
-
-        private void ExportFeeds()
         {
-            // Setup the save file dialog
             var saveFileDialog = new SaveFileDialog
             {
+                FileName = Properties.Resources.ApplicationName,
                 Filter = Properties.Resources.ImportExportFilter,
                 FilterIndex = 0,
                 OverwritePrompt = true
@@ -147,7 +123,6 @@ namespace FeedCenter.Options
             if (!result.GetValueOrDefault(false))
                 return;
 
-            // Setup the writer settings
             var writerSettings = new XmlWriterSettings
             {
                 Indent = true,
@@ -155,48 +130,32 @@ namespace FeedCenter.Options
                 ConformanceLevel = ConformanceLevel.Document
             };
 
-            // Create an XML writer for the file chosen
             var xmlWriter = XmlWriter.Create(saveFileDialog.FileName, writerSettings);
 
-            // Start the opml element
             xmlWriter.WriteStartElement("opml");
-
-            // Start the body element
             xmlWriter.WriteStartElement("body");
 
-            // Loop over each feed
+            foreach (var feed in Database.Entities.Feeds.OrderBy(feed => feed.Name))
-            foreach (var feed in Database.Feeds.OrderBy(feed => feed.Name))
             {
-                // Start the outline element
                 xmlWriter.WriteStartElement("outline");
 
-                // Write the title
                 xmlWriter.WriteAttributeString("title", feed.Title);
-
-                // Write the HTML link
                 xmlWriter.WriteAttributeString("htmlUrl", feed.Link);
-
-                // Write the XML link
                 xmlWriter.WriteAttributeString("xmlUrl", feed.Source);
 
-                // End the outline element
                 xmlWriter.WriteEndElement();
             }
 
-            // End the body element
             xmlWriter.WriteEndElement();
 
-            // End the opml element
             xmlWriter.WriteEndElement();
 
-            // Flush and close the writer
             xmlWriter.Flush();
             xmlWriter.Close();
         }
 
-        private void ImportFeeds()
+        private static void ImportFeeds()
         {
-            // Setup the open file dialog
             var openFileDialog = new OpenFileDialog
             {
                 Filter = Properties.Resources.ImportExportFilter,
@@ -208,44 +167,36 @@ namespace FeedCenter.Options
             if (!result.GetValueOrDefault(false))
                 return;
 
-            // Setup the reader settings
             var xmlReaderSettings = new XmlReaderSettings { IgnoreWhitespace = true };
 
-            // Create an XML reader for the file chosen
             var xmlReader = XmlReader.Create(openFileDialog.FileName, xmlReaderSettings);
 
             try
             {
-                // Read the first node
                 xmlReader.Read();
 
-                // Read the OPML node
                 xmlReader.ReadStartElement("opml");
-
-                // Read the body node
                 xmlReader.ReadStartElement("body");
 
-                // Read all outline nodes
                 while (xmlReader.NodeType != XmlNodeType.EndElement)
                 {
-                    // Create a new feed
+                    var feed = Feed.Create();
-                    var feed = Feed.Create(Database);
+                    feed.Category = Database.Entities.Categories.First(c => c.IsDefault);
-                    feed.Category = Database.Categories.First(c => c.IsDefault);
 
-                    // Loop over all attributes
                     while (xmlReader.MoveToNextAttribute())
                     {
-                        // Handle the attibute
                         switch (xmlReader.Name.ToLower())
                         {
                             case "title":
                                 feed.Title = xmlReader.Value;
                                 break;
 
+                            // ReSharper disable once StringLiteralTypo
                             case "htmlurl":
                                 feed.Link = xmlReader.Value;
                                 break;
 
+                            // ReSharper disable once StringLiteralTypo
                             case "xmlurl":
                                 feed.Source = xmlReader.Value;
                                 break;
@@ -256,24 +207,18 @@ namespace FeedCenter.Options
                         }
                     }
 
-                    // Fill in defaults for optional fields
                     if (string.IsNullOrEmpty(feed.Name))
                         feed.Name = feed.Title;
 
-                    // Add the feed to the main list
+                    Database.Entities.Feeds.Add(feed);
-                    Database.Feeds.Add(feed);
 
-                    // Move back to the element node
                     xmlReader.MoveToElement();
 
-                    // Skip to the next node
                     xmlReader.Skip();
                 }
 
-                // End the body node
                 xmlReader.ReadEndElement();
 
-                // End the OPML node
                 xmlReader.ReadEndElement();
             }
             finally
@@ -282,33 +227,32 @@ namespace FeedCenter.Options
             }
         }
 
-        #endregion
-
-        #region Category list management
-
         private void SetCategoryButtonStates()
         {
             AddCategoryButton.IsEnabled = true;
-            EditCategoryButton.IsEnabled = (CategoryListBox.SelectedItem != null && CategoryListBox.SelectedItem != Database.DefaultCategory);
+
-            DeleteCategoryButton.IsEnabled = (CategoryListBox.SelectedItem != null && CategoryListBox.SelectedItem != Database.DefaultCategory);
+            var selectedId = ((Category) CategoryListBox.SelectedItem).Id;
+
+            EditCategoryButton.IsEnabled = CategoryListBox.SelectedItem != null && selectedId != Database.Entities.DefaultCategory.Id;
+            DeleteCategoryButton.IsEnabled = CategoryListBox.SelectedItem != null && selectedId != Database.Entities.DefaultCategory.Id;
         }
 
         private void AddCategory()
         {
-            var category = Category.Create();
+            var category = new Category();
 
             var categoryWindow = new CategoryWindow();
 
             var result = categoryWindow.Display(category, Window.GetWindow(this));
 
-            if (result.HasValue && result.Value)
+            if (!result.HasValue || !result.Value)
-            {
+                return;
-                Database.SaveChanges(() => Database.Categories.Add(category));
 
-                CategoryListBox.SelectedItem = category;
+            Database.Entities.SaveChanges(() => Database.Entities.Categories.Add(category));
 
-                SetCategoryButtonStates();
+            CategoryListBox.SelectedItem = category;
-            }
+
+            SetCategoryButtonStates();
         }
 
         private void EditSelectedCategory()
@@ -325,7 +269,7 @@ namespace FeedCenter.Options
 
         private void DeleteSelectedCategory()
         {
-            var defaultCategory = Database.DefaultCategory;
+            var defaultCategory = Database.Entities.DefaultCategory;
 
             var category = (Category) CategoryListBox.SelectedItem;
 
@@ -338,15 +282,11 @@ namespace FeedCenter.Options
             else
                 CategoryListBox.SelectedIndex = index + 1;
 
-            Database.SaveChanges(() => Database.Categories.Remove(category));
+            Database.Entities.SaveChanges(() => Database.Entities.Categories.Remove(category));
 
             SetCategoryButtonStates();
         }
 
-        #endregion
-
-        #region Category event handlers
-
         private void HandleAddCategoryButtonClick(object sender, RoutedEventArgs e)
         {
             AddCategory();
@@ -362,15 +302,13 @@ namespace FeedCenter.Options
             DeleteSelectedCategory();
         }
 
-        #endregion
-
         private CollectionViewSource _collectionViewSource;
 
         private void HandleCategoryListBoxSelectionChanged(object sender, SelectionChangedEventArgs e)
         {
             if (_collectionViewSource == null)
             {
-                _collectionViewSource = new CollectionViewSource { Source = Database.Feeds };
+                _collectionViewSource = new CollectionViewSource { Source = Database.Entities.Feeds };
                 _collectionViewSource.SortDescriptions.Add(new SortDescription("Name", ListSortDirection.Ascending));
                 _collectionViewSource.Filter += HandleCollectionViewSourceFilter;
 
@@ -392,16 +330,16 @@ namespace FeedCenter.Options
 
             var feed = (Feed) e.Item;
 
-            e.Accepted = (feed.Category.Id == selectedCategory.Id);
+            e.Accepted = feed.Category.Id == selectedCategory.Id;
         }
 
-        private void HandleTextBlockDrop(object sender, DragEventArgs e)
+        private void CategoryListBox_Drop(object sender, DragEventArgs e)
         {
             var feedList = (List<Feed>) e.Data.GetData(typeof(List<Feed>));
 
             var category = (Category) ((DataGridRow) sender).Item;
 
-            foreach (var feed in feedList)
+            foreach (var feed in feedList!)
                 feed.Category = category;
 
             _collectionViewSource.View.Refresh();
@@ -413,22 +351,22 @@ namespace FeedCenter.Options
 
         private void HandleListBoxItemPreviewMouseMove(object sender, MouseEventArgs e)
         {
-            if (e.LeftButton == MouseButtonState.Pressed)
+            if (e.LeftButton != MouseButtonState.Pressed)
-            {
+                return;
-                var selectedItems = FeedListBox.SelectedItems.Cast<Feed>().ToList();
 
-                DragDrop.DoDragDrop(FeedListBox, selectedItems, DragDropEffects.Move);
+            var selectedItems = FeedListBox.SelectedItems.Cast<Feed>().ToList();
-            }
+
+            DragDrop.DoDragDrop(FeedListBox, selectedItems, DragDropEffects.Move);
         }
 
-        private void HandleTextBlockDragEnter(object sender, DragEventArgs e)
+        private void CategoryListBox_DragEnter(object sender, DragEventArgs e)
         {
             var dataGridRow = (DataGridRow) sender;
 
             dataGridRow.FontWeight = FontWeights.Bold;
         }
 
-        private void HandleTextBlockDragLeave(object sender, DragEventArgs e)
+        private void CategoryListBox_DragLeave(object sender, DragEventArgs e)
         {
             var dataGridRow = (DataGridRow) sender;
 
@@ -443,7 +381,7 @@ namespace FeedCenter.Options
         private void HandleMultipleEditClick(object sender, RoutedEventArgs e)
         {
             var bulkFeedWindow = new BulkFeedWindow();
-            bulkFeedWindow.Display(Window.GetWindow(this), Database);
+            bulkFeedWindow.Display(Window.GetWindow(this));
         }
 
         private void HandleFeedListPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
@@ -458,5 +396,13 @@ namespace FeedCenter.Options
             if (dataGridRow != null && FeedListBox.SelectedItems.Contains(dataGridRow.Item))
                 e.Handled = true;
         }
+
+        private void CategoryListBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
+        {
+            if (!EditCategoryButton.IsEnabled)
+                return;
+
+            EditSelectedCategory();
+        }
     }
-}
+}

Application/Options/GeneralOptionsPanel.xaml

@@ -26,7 +26,8 @@
                   VerticalAlignment="Top"
                   VerticalContentAlignment="Center"
                   Margin="0,5"
-                  Grid.ColumnSpan="2" />
+                  Grid.ColumnSpan="2"
+                  Click="StartWithWindowsCheckBox_Click" />
         <Label Content="{x:Static properties:Resources.defaultBrowserLabel}"
                Target="{Binding ElementName=BrowserComboBox}"
                Grid.Column="0"
@@ -37,7 +38,8 @@
         <ComboBox Name="BrowserComboBox"
                   Grid.Row="2"
                   Grid.Column="1"
-                  VerticalContentAlignment="Center">
+                  VerticalContentAlignment="Center"
+                  SelectionChanged="BrowserComboBox_SelectionChanged">
         </ComboBox>
         <Label Content="{x:Static properties:Resources.defaultUserAgentLabel}"
                Target="{Binding ElementName=BrowserComboBox}"
@@ -49,8 +51,8 @@
         <ComboBox Name="UserAgentComboBox"
                   Grid.Row="4"
                   Grid.Column="1"
-                  VerticalContentAlignment="Center">
+                  VerticalContentAlignment="Center"
+                  SelectionChanged="UserAgentComboBox_SelectionChanged">
         </ComboBox>
-
     </Grid>
-</options:OptionsPanelBase>
+</options:OptionsPanelBase>

Application/Options/GeneralOptionsPanel.xaml.cs

@@ -1,132 +1,104 @@
 using ChrisKaczor.InstalledBrowsers;
 using ChrisKaczor.Wpf.Application;
-using ChrisKaczor.Wpf.Validation;
-using System.Collections.Generic;
 using System.Windows.Controls;
-using System.Windows.Data;
+using System.Windows.Controls.Primitives;
 
-internal class UserAgentItem
+namespace FeedCenter.Options;
-{
-    internal string Caption { get; set; }
-    internal string UserAgent { get; set; }
-}
 
-namespace FeedCenter.Options
+public partial class GeneralOptionsPanel
 {
-    public partial class GeneralOptionsPanel
+    public GeneralOptionsPanel()
     {
-        public GeneralOptionsPanel()
+        InitializeComponent();
+    }
+
+    public override string CategoryName => Properties.Resources.optionCategoryGeneral;
+
+    public override void LoadPanel()
+    {
+        base.LoadPanel();
+
+        var settings = Properties.Settings.Default;
+
+        StartWithWindowsCheckBox.IsChecked = settings.StartWithWindows;
+
+        LoadBrowserComboBox(BrowserComboBox, settings.Browser);
+
+        LoadUserAgentComboBox(UserAgentComboBox, settings.DefaultUserAgent);
+
+        MarkLoaded();
+    }
+
+    private static void LoadBrowserComboBox(Selector selector, string selected)
+    {
+        selector.SelectedIndex = 0;
+
+        ComboBoxItem selectedItem = null;
+
+        var browsers = InstalledBrowser.GetInstalledBrowsers(true);
+        foreach (var browser in browsers)
         {
-            InitializeComponent();
+            var item = new ComboBoxItem { Content = browser.Value.Name, Tag = browser.Key };
+
+            selector.Items.Add(item);
+
+            if (browser.Key == selected)
+                selectedItem = item;
         }
 
-        public override string CategoryName => Properties.Resources.optionCategoryGeneral;
+        if (selectedItem != null)
+            selector.SelectedItem = selectedItem;
+    }
 
-        public override void LoadPanel(FeedCenterEntities database)
+    private static void LoadUserAgentComboBox(Selector selector, string selected)
+    {
+        selector.SelectedIndex = 0;
+
+        ComboBoxItem selectedItem = null;
+
+        var userAgents = UserAgentItem.GetUserAgents();
+        foreach (var userAgent in userAgents)
         {
-            base.LoadPanel(database);
+            var item = new ComboBoxItem { Content = userAgent.Caption, Tag = userAgent.UserAgent };
 
-            var settings = Properties.Settings.Default;
+            selector.Items.Add(item);
 
-            StartWithWindowsCheckBox.IsChecked = settings.StartWithWindows;
+            if (userAgent.UserAgent == selected)
-
+                selectedItem = item;
-            LoadBrowserComboBox(BrowserComboBox, settings.Browser);
-
-            LoadUserAgentComboBox(UserAgentComboBox, settings.DefaultUserAgent);
         }
 
-        public override bool ValidatePanel()
+        if (selectedItem != null)
-        {
+            selector.SelectedItem = selectedItem;
-            return true;
+    }
-        }
 
-        public override void SavePanel()
+    private void StartWithWindowsCheckBox_Click(object sender, System.Windows.RoutedEventArgs e)
-        {
+    {
-            var settings = Properties.Settings.Default;
+        if (!HasLoaded) return;
 
-            if (StartWithWindowsCheckBox.IsChecked.HasValue &&
+        var settings = Properties.Settings.Default;
-                settings.StartWithWindows != StartWithWindowsCheckBox.IsChecked.Value)
-                settings.StartWithWindows = StartWithWindowsCheckBox.IsChecked.Value;
 
-            System.Windows.Application.Current.SetStartWithWindows(settings.StartWithWindows);
+        if (StartWithWindowsCheckBox.IsChecked.HasValue &&
+            settings.StartWithWindows != StartWithWindowsCheckBox.IsChecked.Value)
+            settings.StartWithWindows = StartWithWindowsCheckBox.IsChecked.Value;
 
-            settings.Browser = (string) ((ComboBoxItem) BrowserComboBox.SelectedItem).Tag;
+        System.Windows.Application.Current.SetStartWithWindows(settings.StartWithWindows);
+    }
 
-            settings.DefaultUserAgent = (string) ((ComboBoxItem) UserAgentComboBox.SelectedItem).Tag;
+    private void BrowserComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (!HasLoaded) return;
 
-            var expressions = this.GetBindingExpressions(new[] { UpdateSourceTrigger.Explicit });
+        var settings = Properties.Settings.Default;
-            this.UpdateAllSources(expressions);
-        }
 
-        private static void LoadBrowserComboBox(ComboBox comboBox, string selected)
+        settings.Browser = (string) ((ComboBoxItem) BrowserComboBox.SelectedItem).Tag;
-        {
+    }
-            comboBox.SelectedIndex = 0;
 
-            ComboBoxItem selectedItem = null;
+    private void UserAgentComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (!HasLoaded) return;
 
-            var browsers = InstalledBrowser.GetInstalledBrowsers(true);
+        var settings = Properties.Settings.Default;
-            foreach (var browser in browsers)
-            {
-                var item = new ComboBoxItem { Content = browser.Value.Name, Tag = browser.Key };
 
-                comboBox.Items.Add(item);
+        settings.DefaultUserAgent = (string) ((ComboBoxItem) UserAgentComboBox.SelectedItem).Tag;
-
-                if (browser.Key == selected)
-                    selectedItem = item;
-            }
-
-            if (selectedItem != null)
-                comboBox.SelectedItem = selectedItem;
-        }
-
-        private static void LoadUserAgentComboBox(ComboBox comboBox, string selected)
-        {
-            comboBox.SelectedIndex = 0;
-
-            ComboBoxItem selectedItem = null;
-
-            var userAgents = GetUserAgents();
-            foreach (var userAgent in userAgents)
-            {
-                var item = new ComboBoxItem { Content = userAgent.Caption, Tag = userAgent.UserAgent };
-
-                comboBox.Items.Add(item);
-
-                if (userAgent.UserAgent == selected)
-                    selectedItem = item;
-            }
-
-            if (selectedItem != null)
-                comboBox.SelectedItem = selectedItem;
-        }
-
-        private static List<UserAgentItem> GetUserAgents()
-        {
-            var userAgents = new List<UserAgentItem>
-            {
-                new()
-                {
-                    Caption = Properties.Resources.DefaultUserAgentCaption,
-                    UserAgent = string.Empty
-                },
-                new()
-                {
-                    Caption = "Windows RSS Platform 2.0",
-                    UserAgent = "Windows-RSS-Platform/2.0 (MSIE 9.0; Windows NT 6.1)"
-                },
-                new()
-                {
-                    Caption = "Feedly 1.0",
-                    UserAgent = "Feedly/1.0"
-                },
-                new()
-                {
-                    Caption = "curl",
-                    UserAgent = "curl/7.47.0"
-                }
-            };
-
-            return userAgents;
-        }
     }
 }

Application/Options/OptionsPanelBase.cs

@@ -1,27 +1,19 @@
-using System;
+using System.Windows.Controls;
-using System.Windows.Controls;
 
-namespace FeedCenter.Options
+namespace FeedCenter.Options;
+
+public class OptionsPanelBase : UserControl
 {
-    public class OptionsPanelBase : UserControl
+    public bool HasLoaded { get; private set; }
+
+    public virtual void LoadPanel()
     {
-        protected FeedCenterEntities Database { get; private set; }
-
-        public virtual void LoadPanel(FeedCenterEntities database)
-        {
-            Database = database;
-        }
-
-        public virtual bool ValidatePanel()
-        {
-            throw new NotImplementedException();
-        }
-
-        public virtual void SavePanel()
-        {
-            throw new NotImplementedException();
-        }
-
-        public virtual string CategoryName => null;
     }
-}
+
+    public void MarkLoaded()
+    {
+        HasLoaded = true;
+    }
+
+    public virtual string CategoryName => null;
+}

Application/Options/OptionsWindow.xaml

@@ -17,15 +17,7 @@
         <ContentControl Margin="144,12,12,41"
                         Name="ContentControl"
                         IsTabStop="False" />
-        <Button Content="{x:Static properties:Resources.OkayButton}"
+        <Button Content="{x:Static properties:Resources.CloseButton}"
-                Height="23"
-                HorizontalAlignment="Right"
-                Margin="0,0,93,12"
-                VerticalAlignment="Bottom"
-                Width="75"
-                IsDefault="True"
-                Click="HandleOkayButtonClick" />
-        <Button Content="{x:Static properties:Resources.CancelButton}"
                 Margin="0,0,12,12"
                 Height="23"
                 VerticalAlignment="Bottom"

Application/Options/OptionsWindow.xaml.cs

@@ -1,22 +1,13 @@
 using FeedCenter.Data;
 using System.Collections.Generic;
-using System.Windows;
 using System.Windows.Controls;
 
 namespace FeedCenter.Options
 {
     public partial class OptionsWindow
     {
-        #region Member variables
-
         private readonly List<OptionsPanelBase> _optionPanels = new();
 
-        private readonly FeedCenterEntities _database = Database.Entities;
-
-        #endregion
-
-        #region Constructor
-
         public OptionsWindow()
         {
             InitializeComponent();
@@ -28,10 +19,6 @@ namespace FeedCenter.Options
             LoadCategories();
         }
 
-        #endregion
-
-        #region Category handling
-
         private void AddCategories()
         {
             _optionPanels.Add(new GeneralOptionsPanel());
@@ -47,7 +34,7 @@ namespace FeedCenter.Options
             foreach (var optionsPanel in _optionPanels)
             {
                 // Tell the panel to load itself
-                optionsPanel.LoadPanel(_database);
+                optionsPanel.LoadPanel();
 
                 // Add the panel to the category ist
                 CategoryListBox.Items.Add(new CategoryListItem(optionsPanel));
@@ -72,10 +59,6 @@ namespace FeedCenter.Options
             SelectCategory(((CategoryListItem) CategoryListBox.SelectedItem).Panel);
         }
 
-        #endregion
-
-        #region Category list item
-
         private class CategoryListItem
         {
             public OptionsPanelBase Panel { get; }
@@ -90,40 +73,5 @@ namespace FeedCenter.Options
                 return Panel.CategoryName;
             }
         }
-
-        #endregion
-
-        private void HandleOkayButtonClick(object sender, RoutedEventArgs e)
-        {
-            // Loop over each panel and ask them to validate
-            foreach (var optionsPanel in _optionPanels)
-            {
-                // If validation fails...
-                if (!optionsPanel.ValidatePanel())
-                {
-                    // ...select the right category
-                    SelectCategory(optionsPanel);
-
-                    // Stop validation
-                    return;
-                }
-            }
-
-            // Loop over each panel and ask them to save
-            foreach (var optionsPanel in _optionPanels)
-            {
-                // Save!
-                optionsPanel.SavePanel();
-            }
-
-            // Save the actual settings
-            _database.SaveChanges(() => { });
-            Properties.Settings.Default.Save();
-
-            DialogResult = true;
-
-            // Close the window
-            Close();
-        }
     }
-}
+}

Application/Options/UpdateOptionsPanel.xaml

@@ -11,7 +11,8 @@
     <Grid>
         <CheckBox Content="{x:Static properties:Resources.checkVersionOnStartupCheckBox}"
                   Name="CheckVersionOnStartupCheckBox"
-                  VerticalAlignment="Top" />
+                  VerticalAlignment="Top"
+                  Click="CheckVersionOnStartupCheckBox_Click" />
         <Button Content="{x:Static properties:Resources.checkVersionNowButton}"
                 Height="23"
                 HorizontalAlignment="Left"
@@ -20,4 +21,4 @@
                 Width="75"
                 Click="HandleCheckVersionNowButtonClick" />
     </Grid>
-</options:OptionsPanelBase>
+</options:OptionsPanelBase>

Application/Options/UpdateOptionsPanel.xaml.cs

@@ -1,37 +1,35 @@
 using ChrisKaczor.ApplicationUpdate;
 
-namespace FeedCenter.Options
+namespace FeedCenter.Options;
+
+public partial class UpdateOptionsPanel
 {
-    public partial class UpdateOptionsPanel
+    public UpdateOptionsPanel()
     {
-        public UpdateOptionsPanel()
+        InitializeComponent();
-        {
+    }
-            InitializeComponent();
-        }
 
-        public override void LoadPanel(FeedCenterEntities database)
+    public override void LoadPanel()
-        {
+    {
-            base.LoadPanel(database);
+        base.LoadPanel();
 
-            CheckVersionOnStartupCheckBox.IsChecked = Properties.Settings.Default.CheckVersionAtStartup;
+        CheckVersionOnStartupCheckBox.IsChecked = Properties.Settings.Default.CheckVersionAtStartup;
-        }
 
-        public override bool ValidatePanel()
+        MarkLoaded();
-        {
+    }
-            return true;
-        }
 
-        public override void SavePanel()
+    public override string CategoryName => Properties.Resources.optionCategoryUpdate;
-        {
-            if (CheckVersionOnStartupCheckBox.IsChecked.HasValue && Properties.Settings.Default.CheckVersionAtStartup != CheckVersionOnStartupCheckBox.IsChecked.Value)
-                Properties.Settings.Default.CheckVersionAtStartup = CheckVersionOnStartupCheckBox.IsChecked.Value;
-        }
 
-        public override string CategoryName => Properties.Resources.optionCategoryUpdate;
+    private void HandleCheckVersionNowButtonClick(object sender, System.Windows.RoutedEventArgs e)
+    {
+        UpdateCheck.DisplayUpdateInformation(true);
+    }
 
-        private void HandleCheckVersionNowButtonClick(object sender, System.Windows.RoutedEventArgs e)
+    private void CheckVersionOnStartupCheckBox_Click(object sender, System.Windows.RoutedEventArgs e)
-        {
+    {
-            UpdateCheck.DisplayUpdateInformation(true);
+        if (!HasLoaded) return;
-        }
+
+        if (CheckVersionOnStartupCheckBox.IsChecked.HasValue && Properties.Settings.Default.CheckVersionAtStartup != CheckVersionOnStartupCheckBox.IsChecked.Value)
+            Properties.Settings.Default.CheckVersionAtStartup = CheckVersionOnStartupCheckBox.IsChecked.Value;
     }
 }

Application/Options/UserAgentItem.cs

@@ -0,0 +1,39 @@
+using System.Collections.Generic;
+
+namespace FeedCenter.Options
+{
+    internal class UserAgentItem
+    {
+        internal string Caption { get; set; }
+        internal string UserAgent { get; set; }
+
+        internal static List<UserAgentItem> GetUserAgents()
+        {
+            var userAgents = new List<UserAgentItem>
+            {
+                new()
+                {
+                    Caption = Properties.Resources.DefaultUserAgentCaption,
+                    UserAgent = string.Empty
+                },
+                new()
+                {
+                    Caption = "Windows RSS Platform 2.0",
+                    UserAgent = "Windows-RSS-Platform/2.0 (MSIE 9.0; Windows NT 6.1)"
+                },
+                new()
+                {
+                    Caption = "Feedly 1.0",
+                    UserAgent = "Feedly/1.0"
+                },
+                new()
+                {
+                    Caption = "curl",
+                    UserAgent = "curl/7.47.0"
+                }
+            };
+
+            return userAgents;
+        }
+    }
+}

Application/Properties/Resources.Designer.cs

@@ -214,6 +214,15 @@ namespace FeedCenter.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to _Name:.
+        /// </summary>
+        public static string categoryNameLabel {
+            get {
+                return ResourceManager.GetString("categoryNameLabel", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Add Category.
         /// </summary>

Application/Properties/Resources.resx

@@ -535,4 +535,7 @@
   <data name="SplashMigratingLegacyDatabase" xml:space="preserve">
     <value>Migrating legacy database...</value>
   </data>
+  <data name="categoryNameLabel" xml:space="preserve">
+    <value>_Name:</value>
+  </data>
 </root>

Application/Style.xaml

@@ -1,11 +1,30 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
     <Style TargetType="{x:Type TextBox}">
+        <Setter Property="Validation.ErrorTemplate">
+            <Setter.Value>
+                <ControlTemplate>
+                    <StackPanel Orientation="Horizontal">
+                        <AdornedElementPlaceholder x:Name="placeholder" />
+                        <TextBlock FontSize="14"
+                                   Margin="2,0"
+                                   Foreground="White"
+                                   Background="Red"
+                                   TextAlignment="Center"
+                                   Width="16"
+                                   Text="!"
+                                   ToolTip="{Binding AdornedElement.(Validation.Errors)[0].ErrorContent, ElementName=placeholder}" />
+                    </StackPanel>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
         <Style.Triggers>
             <Trigger Property="Validation.HasError"
                      Value="true">
                 <Setter Property="ToolTip"
                         Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" />
+                <Setter Property="Margin"
+                        Value="0,0,18,0" />
             </Trigger>
         </Style.Triggers>
     </Style>