Added a placeholder text in the text box, and made a few other UI tweaks.

UnicodeCharacterInspector/MainWindow.xaml

@@ -13,7 +13,7 @@
 	<Window.DataContext>
 		<local:CharacterInspectorViewModel />
 	</Window.DataContext>
-    <Grid Margin="10">
+	<Grid Margin="10">
 		<Grid.Resources>
 			<Style TargetType="{x:Type Label}" BasedOn="{StaticResource ResourceKey={x:Type Label}}">
 				<Setter Property="Margin" Value="3" />
@@ -37,7 +37,7 @@
 			<ColumnDefinition Width="120" />
 			<ColumnDefinition Width="*" />
 		</Grid.ColumnDefinitions>
-		<TextBox Grid.ColumnSpan="2" ScrollViewer.VerticalScrollBarVisibility="Auto" MinLines="1" MaxLines="5" AcceptsReturn="True" Text="{Binding Text, UpdateSourceTrigger=PropertyChanged}" />
+		<TextBox Grid.ColumnSpan="2" ScrollViewer.VerticalScrollBarVisibility="Auto" MinLines="1" MaxLines="5" AcceptsTab="True" AcceptsReturn="True" local:Placeholder.Text="Text to analyse" Text="{Binding Text, UpdateSourceTrigger=PropertyChanged}" />
 		<ListBox Grid.Row="1" Grid.RowSpan="3" ItemsSource="{Binding Characters}" SelectedIndex="{Binding SelectedCharacterIndex}">
 			<ListBox.ItemTemplate>
 				<DataTemplate>
@@ -45,7 +45,7 @@
 				</DataTemplate>
 			</ListBox.ItemTemplate>
 		</ListBox>
-		<TextBlock Grid.Row="1" Grid.Column="1" TextOptions.TextFormattingMode="Ideal" TextOptions.TextRenderingMode="Grayscale" Text="{Binding SelectedCharacterInfo.DisplayText}" FontSize="96" HorizontalAlignment="Center" VerticalAlignment="Center" />
+		<TextBlock Grid.Row="1" Grid.Column="1" TextOptions.TextHintingMode="Fixed" TextOptions.TextFormattingMode="Ideal" TextOptions.TextRenderingMode="Grayscale" Text="{Binding SelectedCharacterInfo.DisplayText}" FontSize="96" HorizontalAlignment="Center" VerticalAlignment="Center" />
 		<ScrollViewer Grid.Row="2" Grid.Column="1" VerticalScrollBarVisibility="Auto">
 			<Grid>
 				<Grid.Resources>
@@ -126,11 +126,11 @@
 				<TextBlock Grid.Row="19" Grid.Column="1" Visibility="{Binding SelectedCharacterInfo.UnihanNumericType, Converter={StaticResource ZeroToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.UnihanNumericType}" />
 				<TextBlock Grid.Row="20" Grid.Column="0" Visibility="{Binding SelectedCharacterInfo.NumericValue, Converter={StaticResource NullToVisibilityConverter}}" Text="Numeric Value" />
 				<TextBlock Grid.Row="20" Grid.Column="1" Visibility="{Binding SelectedCharacterInfo.NumericValue, Converter={StaticResource NullToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.NumericValue}" />
-				<TextBlock Grid.Row="21" Grid.Column="0" VerticalAlignment="Top" Visibility="{Binding SelectedCharacterInfo.ContributoryProperties, Converter={StaticResource NullToVisibilityConverter}}" Text="Contributory Properties" />
+				<TextBlock Grid.Row="21" Grid.Column="0" VerticalAlignment="Top" Visibility="{Binding SelectedCharacterInfo.ContributoryProperties, Converter={StaticResource ZeroToVisibilityConverter}}" Text="Contributory Properties" />
-				<TextBlock Grid.Row="21" Grid.Column="1" VerticalAlignment="Top" TextWrapping="WrapWithOverflow" Visibility="{Binding SelectedCharacterInfo.ContributoryProperties, Converter={StaticResource NullToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.ContributoryProperties}" />
+				<TextBlock Grid.Row="21" Grid.Column="1" VerticalAlignment="Top" TextWrapping="WrapWithOverflow" Visibility="{Binding SelectedCharacterInfo.ContributoryProperties, Converter={StaticResource ZeroToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.ContributoryProperties}" />
-				<TextBlock Grid.Row="22" Grid.Column="0" VerticalAlignment="Top" Visibility="{Binding SelectedCharacterInfo.CoreProperties, Converter={StaticResource NullToVisibilityConverter}}" Text="Core Properties" />
+				<TextBlock Grid.Row="22" Grid.Column="0" VerticalAlignment="Top" Visibility="{Binding SelectedCharacterInfo.CoreProperties, Converter={StaticResource ZeroToVisibilityConverter}}" Text="Core Properties" />
-				<TextBlock Grid.Row="22" Grid.Column="1" VerticalAlignment="Top" TextWrapping="WrapWithOverflow" Visibility="{Binding SelectedCharacterInfo.CoreProperties, Converter={StaticResource NullToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.CoreProperties}" />
+				<TextBlock Grid.Row="22" Grid.Column="1" VerticalAlignment="Top" TextWrapping="WrapWithOverflow" Visibility="{Binding SelectedCharacterInfo.CoreProperties, Converter={StaticResource ZeroToVisibilityConverter}}" Text="{Binding SelectedCharacterInfo.CoreProperties}" />
 			</Grid>
 		</ScrollViewer>
-    </Grid>
+	</Grid>
 </Window>

UnicodeCharacterInspector/Placeholder.cs

@@ -0,0 +1,170 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+using System.Windows.Documents;
+using System.Windows.Media;
+
+namespace UnicodeCharacterInspector
+{
+	// Inspired by http://stackoverflow.com/questions/833943/watermark-hint-text-placeholder-textbox-in-wpf
+	internal static partial class Placeholder
+	{
+		public static string GetText(DependencyObject obj)
+		{
+			return (string)obj.GetValue(TextProperty);
+		}
+
+		public static void SetText(DependencyObject obj, string value)
+		{
+			obj.SetValue(TextProperty, value);
+		}
+
+		public static readonly DependencyProperty TextProperty = DependencyProperty.RegisterAttached("Text", typeof(string), typeof(Placeholder), new PropertyMetadata(OnTextChanged));
+
+		private static readonly HashSet<Control> handledControls = new HashSet<Control>();
+
+		private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+		{
+			var control = d as TextBoxBase;
+
+			if (d == null) return;
+
+			if (e.NewValue == null || "".Equals(e.NewValue)) UnregisterControl(control);
+			else UpdateControl(control, (string)e.NewValue);
+		}
+
+		private static void OnControlLoaded(object sender, RoutedEventArgs e)
+		{
+			var control = (Control)sender;
+			UpdateControl(control, GetText(control));
+		}
+
+		private static void OnTextBoxGotKeyboardFocus(object sender, System.Windows.Input.KeyboardFocusChangedEventArgs e)
+		{
+			var control = (Control)sender;
+			RemoveAdorner(control);
+		}
+
+		private static void UpdateControl(Control control, string placeholderText)
+		{
+			if (handledControls.Add(control))
+			{
+				RegisterControl(control);
+			}
+
+			if (IsEmpty(control))
+			{
+				var adorner = GetAdorner(control) ?? AddAdorner(control);
+				if (adorner != null) adorner.Text = placeholderText;
+			}
+			else
+			{
+				RemoveAdorner(control);
+			}
+		}
+
+		private static void RegisterControl(Control control)
+		{
+			control.Loaded += OnControlLoaded;
+
+			var textBox = control as TextBoxBase;
+			if (textBox != null) RegisterTextBox(textBox);
+		}
+
+		private static void RegisterTextBox(TextBoxBase textBox)
+		{
+			textBox.GotKeyboardFocus += OnTextBoxGotKeyboardFocus;
+			textBox.LostKeyboardFocus += OnControlLoaded;
+		}
+
+		private static void UnregisterControl(Control control)
+		{
+			if (handledControls.Remove(control))
+			{
+				control.Loaded -= OnControlLoaded;
+
+				var textBox = control as TextBoxBase;
+				if (textBox != null) UnregisterTextBox(textBox);
+
+				RemoveAdorner(control);
+			}
+		}
+
+		private static void UnregisterTextBox(TextBoxBase textBox)
+		{
+			textBox.GotKeyboardFocus -= OnTextBoxGotKeyboardFocus;
+			textBox.LostKeyboardFocus -= OnControlLoaded;
+		}
+
+		private static bool IsEmpty(Control control)
+		{
+			var textBox = control as TextBox;
+
+			if (textBox != null) return string.IsNullOrEmpty(textBox.Text);
+
+			return false;
+		}
+
+		private static PlaceholderAdorner GetAdorner(Control control)
+		{
+			var layer = AdornerLayer.GetAdornerLayer(control);
+
+			if (layer != null)
+			{
+				var adorners = layer.GetAdorners(control);
+
+				if (adorners != null)
+				{
+					foreach (var adorner in adorners)
+					{
+						var placeholder = adorner as PlaceholderAdorner;
+
+						if (placeholder != null) return placeholder;
+					}
+				}
+			}
+
+			return null;
+		}
+
+		private static PlaceholderAdorner AddAdorner(Control control)
+		{
+			var layer = AdornerLayer.GetAdornerLayer(control);
+
+			if (layer == null) return null;
+
+			var placeholder = new PlaceholderAdorner(control);
+
+			layer.Add(placeholder);
+
+			return placeholder;
+		}
+
+		private static void RemoveAdorner(Control control)
+		{
+			var layer = AdornerLayer.GetAdornerLayer(control);
+
+			if (layer == null) return;
+
+			var adorners = layer.GetAdorners(control);
+
+			if (adorners == null) return;
+
+			foreach (var adorner in adorners)
+			{
+				var placeholder = adorner as PlaceholderAdorner;
+
+				if (placeholder != null)
+				{
+					layer.Remove(placeholder);
+					return;
+				}
+			}
+		}
+	}
+}

UnicodeCharacterInspector/PlaceholderAdorner.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Documents;
+using System.Windows.Media;
+
+namespace UnicodeCharacterInspector
+{
+	internal static partial class Placeholder
+	{
+		private sealed class PlaceholderAdorner : Adorner
+		{
+			public string Text { get; set; }
+
+			public PlaceholderAdorner(UIElement adornedElement)
+				: base(adornedElement)
+			{
+				IsHitTestVisible = false;
+			}
+
+			protected override Visual GetVisualChild(int index) { throw new InvalidOperationException(); }
+
+			protected override int VisualChildrenCount { get { return 0; } }
+
+			protected override void OnRender(DrawingContext drawingContext)
+			{
+				var control = ((Control)AdornedElement);
+
+				Rect adornedElementRect = new Rect(AdornedElement.RenderSize);
+				drawingContext.DrawText
+				(
+					new FormattedText
+					(
+						Text,
+						CultureInfo.CurrentCulture,
+						FlowDirection.LeftToRight,
+						new Typeface
+						(
+							control.FontFamily,
+							control.FontStyle,
+							control.FontWeight,
+							control.FontStretch,
+							SystemFonts.MessageFontFamily
+						),
+						control.FontSize,
+						SystemColors.GrayTextBrush
+					),
+					// The offsets where experimentally determined on a Windows 8.1 machine. I'm willing to accept anything better. 😉
+					new Point(control.BorderThickness.Left + control.Padding.Left + 5, control.BorderThickness.Top + control.Padding.Top + 3)
+				);
+			}
+		}
+	}
+}

UnicodeCharacterInspector/UnicodeCharacterInspector.csproj

@@ -73,6 +73,10 @@
     <Compile Include="BindableObject.cs" />
     <Compile Include="CharacterInfoViewModel.cs" />
     <Compile Include="CharacterInspectorViewModel.cs" />
+    <Compile Include="Placeholder.cs" />
+    <Compile Include="PlaceholderAdorner.cs">
+      <DependentUpon>Placeholder.cs</DependentUpon>
+    </Compile>
     <Compile Include="ZeroToVisibilityConverter.cs" />
     <Compile Include="MainWindow.xaml.cs">
       <DependentUpon>MainWindow.xaml</DependentUpon>