Add time zones settings panel

Data.cs

@@ -0,0 +1,21 @@
+using System.Collections.ObjectModel;
+using System.Text.Json;
+using WorldClockStatusWindow.Properties;
+
+namespace WorldClockStatusWindow;
+
+internal static class Data
+{
+    internal static ObservableCollection<TimeZoneEntry> TimeZoneEntries { get; set; }
+
+    internal static void Load()
+    {
+        TimeZoneEntries = JsonSerializer.Deserialize<ObservableCollection<TimeZoneEntry>>(Settings.Default.TimeZones);
+    }
+
+    internal static void Save()
+    {
+        Settings.Default.TimeZones = JsonSerializer.Serialize(TimeZoneEntries);
+        Settings.Default.Save();
+    }
+}

DataErrorDictionary.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.ComponentModel;
+
+namespace WorldClockStatusWindow;
+
+internal class DataErrorDictionary : Dictionary<string, List<string>>
+{
+    public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
+
+    private void OnErrorsChanged(string propertyName)
+    {
+        ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
+    }
+
+    public IEnumerable GetErrors(string propertyName)
+    {
+        return TryGetValue(propertyName, out var value) ? value : null;
+    }
+
+    public void AddError(string propertyName, string error)
+    {
+        if (!ContainsKey(propertyName))
+            this[propertyName] = [];
+
+        if (this[propertyName].Contains(error))
+            return;
+
+        this[propertyName].Add(error);
+        OnErrorsChanged(propertyName);
+    }
+
+    public void ClearErrors(string propertyName)
+    {
+        if (!ContainsKey(propertyName))
+            return;
+
+        Remove(propertyName);
+        OnErrorsChanged(propertyName);
+    }
+}

Properties/Resources.Designer.cs

@@ -60,6 +60,24 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Add.
+        /// </summary>
+        public static string AddTimeZoneLink {
+            get {
+                return ResourceManager.GetString("AddTimeZoneLink", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Add Time Zone.
+        /// </summary>
+        public static string AddTimeZoneToolTip {
+            get {
+                return ResourceManager.GetString("AddTimeZoneToolTip", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized resource of type System.Drawing.Icon similar to (Icon).
         /// </summary>
@@ -79,6 +97,15 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Cancel.
+        /// </summary>
+        public static string CancelButton {
+            get {
+                return ResourceManager.GetString("CancelButton", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Checking for update....
         /// </summary>
@@ -124,6 +151,42 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Are you sure you want to delete the selected time zones?.
+        /// </summary>
+        public static string ConfirmDeleteTimeZones {
+            get {
+                return ResourceManager.GetString("ConfirmDeleteTimeZones", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Confirm Delete.
+        /// </summary>
+        public static string ConfirmDeleteTitle {
+            get {
+                return ResourceManager.GetString("ConfirmDeleteTitle", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Delete.
+        /// </summary>
+        public static string DeleteTimeZoneLink {
+            get {
+                return ResourceManager.GetString("DeleteTimeZoneLink", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Delete Time Zone.
+        /// </summary>
+        public static string DeleteTimeZoneToolTip {
+            get {
+                return ResourceManager.GetString("DeleteTimeZoneToolTip", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Downloading update....
         /// </summary>
@@ -133,6 +196,24 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Edit.
+        /// </summary>
+        public static string EditTimeZoneLink {
+            get {
+                return ResourceManager.GetString("EditTimeZoneLink", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Edit Time Zone.
+        /// </summary>
+        public static string EditTimeZoneToolTip {
+            get {
+                return ResourceManager.GetString("EditTimeZoneToolTip", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Installing update....
         /// </summary>
@@ -142,6 +223,15 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Label.
+        /// </summary>
+        public static string LabelColumnHeader {
+            get {
+                return ResourceManager.GetString("LabelColumnHeader", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Loading....
         /// </summary>
@@ -151,6 +241,15 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to OK.
+        /// </summary>
+        public static string OkayButton {
+            get {
+                return ResourceManager.GetString("OkayButton", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to About.
         /// </summary>
@@ -169,6 +268,15 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Time Zones.
+        /// </summary>
+        public static string optionCategoryTimeZones {
+            get {
+                return ResourceManager.GetString("optionCategoryTimeZones", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Update.
         /// </summary>
@@ -196,6 +304,33 @@ namespace WorldClockStatusWindow.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Time Zone.
+        /// </summary>
+        public static string TimeZoneColumnHeader {
+            get {
+                return ResourceManager.GetString("TimeZoneColumnHeader", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Add Time Zone.
+        /// </summary>
+        public static string TimeZoneWindowAdd {
+            get {
+                return ResourceManager.GetString("TimeZoneWindowAdd", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Edit Time Zone.
+        /// </summary>
+        public static string TimeZoneWindowEdit {
+            get {
+                return ResourceManager.GetString("TimeZoneWindowEdit", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to You are already running the most recent version.
         ///
@@ -208,7 +343,7 @@ namespace WorldClockStatusWindow.Properties {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Version {1} of {0} is now available.
+        ///   Looks up a localized string similar to Version {0} is now available.
         ///
         ///Would you like to download and install it now?.
         /// </summary>

Properties/Resources.resx

@@ -179,4 +179,49 @@ Would you like to download and install it now?</value>
   <data name="InstallingUpdate" xml:space="preserve">
     <value>Installing update...</value>
   </data>
+  <data name="optionCategoryTimeZones" xml:space="preserve">
+    <value>Time Zones</value>
+  </data>
+  <data name="LabelColumnHeader" xml:space="preserve">
+    <value>Label</value>
+  </data>
+  <data name="TimeZoneColumnHeader" xml:space="preserve">
+    <value>Time Zone</value>
+  </data>
+  <data name="AddTimeZoneLink" xml:space="preserve">
+    <value>Add</value>
+  </data>
+  <data name="EditTimeZoneLink" xml:space="preserve">
+    <value>Edit</value>
+  </data>
+  <data name="DeleteTimeZoneLink" xml:space="preserve">
+    <value>Delete</value>
+  </data>
+  <data name="AddTimeZoneToolTip" xml:space="preserve">
+    <value>Add Time Zone</value>
+  </data>
+  <data name="EditTimeZoneToolTip" xml:space="preserve">
+    <value>Edit Time Zone</value>
+  </data>
+  <data name="DeleteTimeZoneToolTip" xml:space="preserve">
+    <value>Delete Time Zone</value>
+  </data>
+  <data name="ConfirmDeleteTitle" xml:space="preserve">
+    <value>Confirm Delete</value>
+  </data>
+  <data name="ConfirmDeleteTimeZones" xml:space="preserve">
+    <value>Are you sure you want to delete the selected time zones?</value>
+  </data>
+  <data name="TimeZoneWindowAdd" xml:space="preserve">
+    <value>Add Time Zone</value>
+  </data>
+  <data name="TimeZoneWindowEdit" xml:space="preserve">
+    <value>Edit Time Zone</value>
+  </data>
+  <data name="OkayButton" xml:space="preserve">
+    <value>OK</value>
+  </data>
+  <data name="CancelButton" xml:space="preserve">
+    <value>Cancel</value>
+  </data>
 </root>

SettingsWindow/TimeZoneWindow.xaml

@@ -0,0 +1,83 @@
+<Window x:Class="WorldClockStatusWindow.SettingsWindow.TimeZoneWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:properties="clr-namespace:WorldClockStatusWindow.Properties"
+        xmlns:worldClockStatusWindow="clr-namespace:WorldClockStatusWindow"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        d:DataContext="{d:DesignInstance Type=worldClockStatusWindow:TimeZoneEntry}"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:mah="http://metro.mahapps.com/winfx/xaml/controls"
+        xmlns:windows="clr-namespace:ChrisKaczor.Wpf.Windows;assembly=ChrisKaczor.Wpf.Windows.CategoryWindow"
+        mc:Ignorable="d"
+        Title="TimeZoneWindow"
+        ResizeMode="NoResize"
+        SizeToContent="Height"
+        Width="450"
+        WindowStartupLocation="CenterOwner"
+        Icon="/WorldClockStatusWindow;component/Resources/Application.ico"
+        FocusManager.FocusedElement="{Binding ElementName=LabelTextBox}">
+    <Window.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.FlatButton.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Themes/light.cobalt.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Window.Resources>
+    <Grid Margin="6">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="*" />
+        </Grid.ColumnDefinitions>
+        <StackPanel Margin="0,4"
+                    windows:Spacing.Vertical="8">
+            <TextBox Name="LabelTextBox"
+                     mah:TextBoxHelper.UseFloatingWatermark="True"
+                     mah:TextBoxHelper.Watermark="{x:Static properties:Resources.LabelColumnHeader}"
+                     mah:TextBoxHelper.SelectAllOnFocus="True"
+                     Text="{Binding Path=Label, UpdateSourceTrigger=Explicit, ValidatesOnExceptions=True}" />
+            <ComboBox Name="TimeZoneComboBox"
+                      DisplayMemberPath="DisplayName"
+                      SelectedValuePath="Id"
+                      SelectedValue="{Binding Path=TimeZoneId}"
+                      VirtualizingPanel.IsVirtualizing="False"
+                      mah:TextBoxHelper.UseFloatingWatermark="True"
+                      mah:TextBoxHelper.Watermark="{x:Static properties:Resources.TimeZoneColumnHeader}" />
+        </StackPanel>
+        <StackPanel Grid.Column="0"
+                    Grid.Row="1"
+                    Orientation="Horizontal"
+                    Margin="0,5,0,0"
+                    HorizontalAlignment="Right">
+            <Button Content="{x:Static properties:Resources.OkayButton}"
+                    HorizontalAlignment="Right"
+                    VerticalAlignment="Bottom"
+                    Width="75"
+                    Margin="0,0,5,0"
+                    IsDefault="True"
+                    Click="HandleOkayButtonClick">
+                <Button.Style>
+                    <Style TargetType="Button" BasedOn="{StaticResource {x:Type Button}}">
+                        <Style.Triggers>
+                            <DataTrigger Binding="{Binding Text.Length, ElementName=LabelTextBox}"
+                                         Value="0">
+                                <Setter Property="IsEnabled"
+                                        Value="False" />
+                            </DataTrigger>
+                        </Style.Triggers>
+                    </Style>
+                </Button.Style>
+            </Button>
+            <Button Content="{x:Static properties:Resources.CancelButton}"
+                    HorizontalAlignment="Right"
+                    VerticalAlignment="Bottom"
+                    Width="75"
+                    IsCancel="True" />
+        </StackPanel>
+    </Grid>
+</Window>

SettingsWindow/TimeZoneWindow.xaml.cs

@@ -0,0 +1,43 @@
+using ChrisKaczor.Wpf.Validation;
+using System;
+using System.Windows;
+
+namespace WorldClockStatusWindow.SettingsWindow;
+
+public partial class TimeZoneWindow
+{
+    public TimeZoneWindow()
+    {
+        InitializeComponent();
+    }
+
+    public bool? Display(TimeZoneEntry timeZoneEntry, Window owner)
+    {
+        DataContext = timeZoneEntry;
+
+        TimeZoneComboBox.ItemsSource = TimeZoneInfo.GetSystemTimeZones();
+
+        Title = string.IsNullOrWhiteSpace(timeZoneEntry.Label) ? Properties.Resources.TimeZoneWindowAdd : Properties.Resources.TimeZoneWindowEdit;
+
+        Owner = owner;
+
+        return ShowDialog();
+    }
+
+    private void HandleOkayButtonClick(object sender, RoutedEventArgs e)
+    {
+        if (!this.IsValid())
+            return;
+
+        var timeZoneEntry = (TimeZoneEntry)DataContext;
+
+        if (!Data.TimeZoneEntries.Contains(timeZoneEntry))
+            Data.TimeZoneEntries.Add(timeZoneEntry);
+
+        Data.Save();
+
+        DialogResult = true;
+
+        Close();
+    }
+}

SettingsWindow/TimeZonesSettingsPanel.xaml

@@ -0,0 +1,90 @@
+<windows:CategoryPanelBase x:Class="WorldClockStatusWindow.SettingsWindow.TimeZonesSettingsPanel"
+                           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+                           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+                           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+                           xmlns:properties="clr-namespace:WorldClockStatusWindow.Properties"
+                           xmlns:worldClockStatusWindow="clr-namespace:WorldClockStatusWindow"
+                           xmlns:windows="clr-namespace:ChrisKaczor.Wpf.Windows;assembly=ChrisKaczor.Wpf.Windows.CategoryWindow"
+                           xmlns:controls="clr-namespace:ChrisKaczor.Wpf.Controls;assembly=ChrisKaczor.Wpf.Controls.Link"
+                           mc:Ignorable="d"
+                           d:DesignHeight="150"
+                           d:DesignWidth="300">
+    <windows:CategoryPanelBase.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.FlatButton.xaml" />
+                <ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Themes/light.cobalt.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </windows:CategoryPanelBase.Resources>
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="*" />
+        </Grid.ColumnDefinitions>
+        <DataGrid Name="TimeZoneDataGrid"
+                  SelectionMode="Extended"
+                  Grid.Column="0"
+                  Grid.Row="0"
+                  AutoGenerateColumns="False"
+                  GridLinesVisibility="None"
+                  CanUserResizeRows="False"
+                  IsReadOnly="True"
+                  SelectionUnit="FullRow"
+                  HeadersVisibility="Column"
+                  BorderThickness="1,1,1,1"
+                  BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}"
+                  Background="{x:Null}"
+                  SelectionChanged="HandleTimeZoneDataGridSelectionChanged"
+                  d:DataContext="{d:DesignInstance worldClockStatusWindow:TimeZoneEntry }">
+            <DataGrid.Columns>
+                <DataGridTextColumn Binding="{Binding Path=Label}"
+                                    Header="{x:Static properties:Resources.LabelColumnHeader}"
+                                    SortDirection="Ascending"
+                                    Width="*" />
+                <DataGridTextColumn Binding="{Binding TimeZoneId}"
+                                    Header="{x:Static properties:Resources.TimeZoneColumnHeader}"
+                                    Width="*" />
+            </DataGrid.Columns>
+            <DataGrid.RowStyle>
+                <Style TargetType="DataGridRow"
+                       BasedOn="{StaticResource MahApps.Styles.DataGridRow}">
+                    <EventSetter Event="MouseDoubleClick"
+                                 Handler="HandleTimeZoneDataGridRowMouseDoubleClick" />
+                </Style>
+            </DataGrid.RowStyle>
+        </DataGrid>
+        <Border Grid.Column="0"
+                Grid.Row="1"
+                BorderThickness="1,0,1,1"
+                BorderBrush="{DynamicResource {x:Static SystemColors.ActiveBorderBrushKey}}">
+            <StackPanel Orientation="Horizontal"
+                        Background="{DynamicResource {x:Static SystemColors.ControlBrushKey}}">
+                <controls:Link Name="AddTimeZoneButton"
+                               Margin="2"
+                               Click="HandleAddTimeZoneButtonClick"
+                               Text="{x:Static properties:Resources.AddTimeZoneLink}"
+                               ToolTip="{x:Static properties:Resources.AddTimeZoneToolTip}">
+                </controls:Link>
+                <controls:Link Name="EditTimeZoneButton"
+                               Margin="2"
+                               Click="HandleEditTimeZoneButtonClick"
+                               Text="{x:Static properties:Resources.EditTimeZoneLink}"
+                               ToolTip="{x:Static properties:Resources.EditTimeZoneToolTip}">
+                </controls:Link>
+                <controls:Link Name="DeleteTimeZoneButton"
+                               Margin="2"
+                               Click="HandleDeleteTimeZoneButtonClick"
+                               Text="{x:Static properties:Resources.DeleteTimeZoneLink}"
+                               ToolTip="{x:Static properties:Resources.DeleteTimeZoneToolTip}">
+                </controls:Link>
+            </StackPanel>
+        </Border>
+    </Grid>
+</windows:CategoryPanelBase>

SettingsWindow/TimeZonesSettingsPanel.xaml.cs

@@ -0,0 +1,115 @@
+using System;
+using System.ComponentModel;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Input;
+
+namespace WorldClockStatusWindow.SettingsWindow;
+
+public partial class TimeZonesSettingsPanel
+{
+    private CollectionViewSource _collectionViewSource;
+
+    public TimeZonesSettingsPanel()
+    {
+        InitializeComponent();
+    }
+
+    public override string CategoryName => Properties.Resources.optionCategoryTimeZones;
+
+    public override void LoadPanel(Window parentWindow)
+    {
+        base.LoadPanel(parentWindow);
+
+        if (_collectionViewSource == null)
+        {
+            _collectionViewSource = new CollectionViewSource { Source = Data.TimeZoneEntries };
+            _collectionViewSource.SortDescriptions.Add(new SortDescription("Label", ListSortDirection.Ascending));
+
+            TimeZoneDataGrid.ItemsSource = _collectionViewSource.View;
+        }
+
+        _collectionViewSource.View.Refresh();
+
+        if (TimeZoneDataGrid.Items.Count > 0)
+            TimeZoneDataGrid.SelectedIndex = 0;
+
+        SetTimeZoneButtonStates();
+    }
+
+    private void HandleTimeZoneDataGridSelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        SetTimeZoneButtonStates();
+    }
+
+    private void SetTimeZoneButtonStates()
+    {
+        AddTimeZoneButton.IsEnabled = true;
+        EditTimeZoneButton.IsEnabled = TimeZoneDataGrid.SelectedItems.Count == 1;
+        DeleteTimeZoneButton.IsEnabled = TimeZoneDataGrid.SelectedItems.Count > 0;
+    }
+
+    private void HandleAddTimeZoneButtonClick(object sender, RoutedEventArgs e)
+    {
+        AddTimeZone();
+    }
+
+    private void HandleEditTimeZoneButtonClick(object sender, RoutedEventArgs e)
+    {
+        EditSelectedTimeZone();
+    }
+
+    private void HandleDeleteTimeZoneButtonClick(object sender, RoutedEventArgs e)
+    {
+        DeleteSelectedTimeZones();
+    }
+
+    private void HandleTimeZoneDataGridRowMouseDoubleClick(object sender, MouseButtonEventArgs e)
+    {
+        EditSelectedTimeZone();
+    }
+
+    private void AddTimeZone()
+    {
+        var timeZoneEntry = new TimeZoneEntry { TimeZoneId = TimeZoneInfo.Local.Id };
+
+        var timeZoneWindow = new TimeZoneWindow();
+
+        var result = timeZoneWindow.Display(timeZoneEntry, Window.GetWindow(this));
+
+        if (!result.HasValue || !result.Value)
+            return;
+
+        TimeZoneDataGrid.SelectedItem = timeZoneEntry;
+
+        SetTimeZoneButtonStates();
+    }
+
+    private void EditSelectedTimeZone()
+    {
+        if (TimeZoneDataGrid.SelectedItem == null)
+            return;
+
+        var timeZoneEntry = (TimeZoneEntry) TimeZoneDataGrid.SelectedItem;
+
+        var timeZoneWindow = new TimeZoneWindow();
+
+        timeZoneWindow.Display(timeZoneEntry, Window.GetWindow(this));
+    }
+
+    private void DeleteSelectedTimeZones()
+    {
+        if (MessageBox.Show(ParentWindow!, Properties.Resources.ConfirmDeleteTimeZones, Properties.Resources.ConfirmDeleteTitle, MessageBoxButton.YesNo, MessageBoxImage.Question, MessageBoxResult.No) == MessageBoxResult.No)
+            return;
+
+        var selectedItems = new TimeZoneEntry[TimeZoneDataGrid.SelectedItems.Count];
+
+        TimeZoneDataGrid.SelectedItems.CopyTo(selectedItems, 0);
+
+        foreach (var timeZoneEntry in selectedItems)
+            Data.TimeZoneEntries.Remove(timeZoneEntry);
+
+        SetTimeZoneButtonStates();
+    }
+}

TimeZoneEntry.cs

@@ -1,7 +1,61 @@
-namespace WorldClockStatusWindow;
+using System;
+using System.Collections;
+using System.ComponentModel;
+using System.Linq;
+using System.Text.Json.Serialization;
 
-public class TimeZoneEntry
+namespace WorldClockStatusWindow;
+
+public class TimeZoneEntry : INotifyDataErrorInfo
 {
-    public string Label { get; set; }
+    private readonly DataErrorDictionary _dataErrorDictionary;
+
+    public TimeZoneEntry()
+    {
+        _dataErrorDictionary = new DataErrorDictionary();
+        _dataErrorDictionary.ErrorsChanged += DataErrorDictionaryErrorsChanged;
+    }
+
+    private string _label;
+
+    public string Label
+    {
+        get => _label;
+        set
+        {
+            if (!ValidateLabel(value))
+                return;
+
+            _label = value;
+        }
+    }
+
     public string TimeZoneId { get; set; }
+
+    [JsonIgnore]
+    public bool HasErrors => _dataErrorDictionary.Any();
+
+    public IEnumerable GetErrors(string propertyName)
+    {
+        return _dataErrorDictionary.GetErrors(propertyName);
+    }
+
+    public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
+
+    private void DataErrorDictionaryErrorsChanged(object sender, DataErrorsChangedEventArgs e)
+    {
+        ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(e.PropertyName));
+    }
+
+    private bool ValidateLabel(string newValue)
+    {
+        _dataErrorDictionary.ClearErrors(nameof(Label));
+
+        if (!string.IsNullOrWhiteSpace(newValue))
+            return true;
+
+        _dataErrorDictionary.AddError(nameof(Label), "Label cannot be empty");
+
+        return false;
+    }
 }

WindowSource.cs

@@ -5,7 +5,6 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
-using System.Text.Json;
 using System.Threading.Tasks;
 using System.Timers;
 using System.Windows.Threading;
@@ -20,8 +19,6 @@ internal class WindowSource : IWindowSource, IDisposable
     private readonly Timer _timer;
     private readonly Dispatcher _dispatcher;
 
-    private List<TimeZoneEntry> _timeZoneEntries;
-
     internal WindowSource()
     {
         _floatingStatusWindow = new FloatingStatusWindow(this);
@@ -90,36 +87,27 @@ internal class WindowSource : IWindowSource, IDisposable
         _timer.Enabled = true;
     }
 
-    private void Load()
+    private static void Load()
     {
-        _timeZoneEntries = JsonSerializer.Deserialize<List<TimeZoneEntry>>(Settings.Default.TimeZones);
+        Data.Load();
-
-        if (_timeZoneEntries.Any())
-            return;
-
-        _timeZoneEntries.Add(new TimeZoneEntry { Label = "UTC", TimeZoneId = "UTC" });
-        _timeZoneEntries.Add(new TimeZoneEntry { Label = "IST", TimeZoneId = "India Standard Time" });
-        _timeZoneEntries.Add(new TimeZoneEntry { Label = "CET", TimeZoneId = "Central Europe Standard Time" });
-        _timeZoneEntries.Add(new TimeZoneEntry { Label = "Local", TimeZoneId = string.Empty });
-
-        Save();
     }
 
-    private void Save()
+    private static void Save()
     {
-        Settings.Default.TimeZones = JsonSerializer.Serialize(_timeZoneEntries);
+        Data.Save();
-        Settings.Default.Save();
     }
 
     private void HandleTimerElapsed(object sender, ElapsedEventArgs e)
     {
         var text = new StringBuilder();
 
+        if (Data.TimeZoneEntries.Any())
+        {
             var now = DateTimeOffset.Now;
 
-        var labelLength = _timeZoneEntries.Max(x => x.Label.Length);
+            var labelLength = Data.TimeZoneEntries.Max(x => x.Label.Length);
 
-        foreach (var timeZoneEntry in _timeZoneEntries)
+            foreach (var timeZoneEntry in Data.TimeZoneEntries)
             {
                 var timeZone = timeZoneEntry.TimeZoneId == string.Empty ? TimeZoneInfo.Local : TimeZoneInfo.FindSystemTimeZoneById(timeZoneEntry.TimeZoneId);
 
@@ -128,6 +116,7 @@ internal class WindowSource : IWindowSource, IDisposable
 
                 text.Append($"{timeZoneEntry.Label.PadLeft(labelLength)}: {TimeZoneInfo.ConvertTime(now, timeZone).ToString(Settings.Default.TimeFormat)}");
             }
+        }
 
         _dispatcher.Invoke(() => _floatingStatusWindow.SetText(text.ToString()));
     }
@@ -160,6 +149,7 @@ internal class WindowSource : IWindowSource, IDisposable
         var categoryPanels = new List<CategoryPanelBase>
         {
             new GeneralSettingsPanel(),
+            new TimeZonesSettingsPanel(),
             new UpdateSettingsPanel(),
             new AboutSettingsPanel()
         };

WorldClockStatusWindow.csproj

@@ -12,10 +12,12 @@
 		<AppDesigner Include="Properties\" />
 	</ItemGroup>
 	<ItemGroup>
-		<Content Include="Resources\Application.ico" />
+		<Resource Include="Resources\Application.ico" />
 	</ItemGroup>
 	<ItemGroup>
 		<PackageReference Include="ChrisKaczor.Wpf.Application.StartWithWindows" Version="1.0.5" />
+		<PackageReference Include="ChrisKaczor.Wpf.Controls.Link" Version="1.0.4" />
+		<PackageReference Include="ChrisKaczor.Wpf.Validation" Version="1.0.4" />
 		<PackageReference Include="ChrisKaczor.Wpf.Windows.CategoryWindow" Version="1.0.2" />
 		<PackageReference Include="ChrisKaczor.Wpf.Windows.FloatingStatusWindow" Version="2.0.0.5" />
 		<PackageReference Include="Microsoft.CSharp" Version="4.7.0" />