I have a question for you: I'm trying to bind 2 strings, one from the user control to the code-behind of the window.

This is the usercontrol style:

<UserControl
     x:Class="PasswordManager.Helpers.Resource_UserDefined.TextBox_Hint"
     xmlns=";
     xmlns:x=";
     xmlns:d=";
     xmlns:local="clr-name"
     xmlns:mc=";
     Name="TextBoxUserWindow"
     d:DesignHeight="60" d:DesignWidth="800"
     mc:Ignorable="d">

<Grid Margin="20,0,20,0">

    <TextBox
        Name="txtSearchBox"
        Padding="0,0,0,3"
        VerticalContentAlignment="Center"
        Background="{Binding Background, RelativeSource={RelativeSource AncestorType=UserControl}}"
        BorderBrush="{Binding BorderColorBrush, RelativeSource={RelativeSource AncestorType=UserControl}}"
        BorderThickness="{Binding BorderThickness, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontFamily="{Binding FontFamily, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontSize="{Binding FontSize, RelativeSource={RelativeSource AncestorType=UserControl}}"
        Text="{Binding TextBase, RelativeSource={RelativeSource AncestorType=UserControl}}"
        TextChanged="txtSearchBox_TextChanged" />

    <TextBlock
        x:Name="txt_HintBox"
        Margin="3,0,0,0"
        VerticalAlignment="Center"
        Background="Transparent"
        FontFamily="{Binding FontFamily, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontSize="{Binding FontSize, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontStyle="{Binding FontStyle, RelativeSource={RelativeSource AncestorType=UserControl}}"
        Foreground="{Binding ForegroundColorOverlay, RelativeSource={RelativeSource AncestorType=UserControl}}"
        IsHitTestVisible="False"
        Text="{Binding Hint, ElementName=TextBoxUserWindow}" />
    </Grid>
</UserControl>

This is the code-behind file of the user control:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace PasswordManager.Helpers.Resource_UserDefined
{
    public partial class TextBox_Hint : UserControl, INotifyPropertyChanged
    {
        public TextBox_Hint()
        {
            InitializeComponent();
        }

        public string TextBase
        {
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); OnPropertyChanged(); }
        }

        // Using a DependencyProperty as the backing store for TextBase. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty TextProperty = DependencyProperty.Register("TextBase", typeof(string), typeof(TextBox_Hint));

        public string Hint
        {
            get { return (string)GetValue(HintProperty); }
            set { SetValue(HintProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Hint. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty HintProperty = DependencyProperty.Register("Hint", typeof(string), typeof(TextBox_Hint), new PropertyMetadata(""));

        public Brush Background
        {
            get { return (Brush)GetValue(BackgroundProperty); }
            set { SetValue(BackgroundProperty, value); }
        }

        // Using a DependencyProperty as the backing store for background. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackgroundProperty = DependencyProperty.Register("Background", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.White));

        public Brush BorderColorBrush
        {
            get { return (Brush)GetValue(BorderColorBrushProperty); }
            set { SetValue(BorderColorBrushProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BorderColorBrush. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BorderColorBrushProperty = DependencyProperty.Register("BorderColorBrush", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.Black));

        public Thickness BorderThickness
        {
            get { return (Thickness)GetValue(BorderThicknessProperty); }
            set { SetValue(BorderThicknessProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BorderThickness. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BorderThicknessProperty = DependencyProperty.Register("BorderThickness", typeof(Thickness), typeof(TextBox_Hint), new PropertyMetadata(new Thickness(1,1,1,1)));

        public Brush ForegroundColorOverlay
        {
            get { return (Brush)GetValue(ForegroundColorOverlayProperty); }
            set { SetValue(ForegroundColorOverlayProperty, value); }
        }

        // Usando un DependencyProperty come memorizzazione per ForegroundColorOverlay
        public static readonly DependencyProperty ForegroundColorOverlayProperty = DependencyProperty.Register("ForegroundColorOverlay", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.Gray));

        public FontFamily FontFamily
        {
            get { return (FontFamily)GetValue(FontFamilyProperty); }
            set { SetValue(FontFamilyProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontFamily. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontFamilyProperty = DependencyProperty.Register("FontFamily", typeof(FontFamily), typeof(TextBox_Hint), new PropertyMetadata(new FontFamily("Arial")));

        public FontStyle FontStyle
        {
            get { return (FontStyle)GetValue(FontStyleProperty); }
            set { SetValue(FontStyleProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontStyle. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontStyleProperty = DependencyProperty.Register("FontStyle", typeof(FontStyle), typeof(TextBox_Hint), new PropertyMetadata(FontStyles.Normal));

        public Double FontSize
        {
            get { return (Double)GetValue(FontSizeProperty); }
            set { SetValue(FontSizeProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontSize. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontSizeProperty = DependencyProperty.Register("FontSize", typeof(Double), typeof(TextBox_Hint), new PropertyMetadata(20.0));

        private void txtSearchBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (string.IsNullOrEmpty(txtSearchBox.Text))
                txt_HintBox.Visibility = Visibility.Visible;
            else
                txt_HintBox.Visibility = Visibility.Hidden;
        }

        public event PropertyChangedEventHandler? PropertyChanged;

        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

I use the user control like this:

<userControls:TextBox_Hint
x:Name="TextBox_Reame"
Height="40"
BorderColorBrush="Black"
BorderThickness="0,0,0,1"
FontFamily="{DynamicResource Abel}"
FontSize="20"
FontStyle="Italic"
ForegroundColorOverlay="Gray"
Hint="Inserisci Il Reame"
TextBase="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type userControls:TextBox_Hint}}, Path=TextBase}">
<userControls:TextBox_Hint.Background>
    <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
        <GradientStop Offset="0.0" Color="White" />
        <GradientStop Offset="0.5" Color="#FFE1FFE6" />
        <GradientStop Offset="1.0" Color="White" />
    </LinearGradientBrush>
</userControls:TextBox_Hint.Background>
  </userControls:TextBox_Hint>

This is the string property:

    private string _Reame;

    public string Reame
    {
        get { return _Reame; }
        set { _Reame = value; OnPropertyChanged(); }
    }

Now the problem start. I've tried 1000 times to try to fix the issues but with no response. My question is quite simple I think... how can I get the TextBase value (of the user control) directly into my code-behind of the window where I'm using it?

If I use TextBox_Reame.TextBase, I can perfectly get the value, but I want to use binding. I'm not interested in view model for this window because the low data values.

Thanks to everyone

I have a question for you: I'm trying to bind 2 strings, one from the user control to the code-behind of the window.

This is the usercontrol style:

<UserControl
     x:Class="PasswordManager.Helpers.Resource_UserDefined.TextBox_Hint"
     xmlns="http://schemas.microsoft/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft/winfx/2006/xaml"
     xmlns:d="http://schemas.microsoft/expression/blend/2008"
     xmlns:local="clr-name"
     xmlns:mc="http://schemas.openxmlformats./markup-compatibility/2006"
     Name="TextBoxUserWindow"
     d:DesignHeight="60" d:DesignWidth="800"
     mc:Ignorable="d">

<Grid Margin="20,0,20,0">

    <TextBox
        Name="txtSearchBox"
        Padding="0,0,0,3"
        VerticalContentAlignment="Center"
        Background="{Binding Background, RelativeSource={RelativeSource AncestorType=UserControl}}"
        BorderBrush="{Binding BorderColorBrush, RelativeSource={RelativeSource AncestorType=UserControl}}"
        BorderThickness="{Binding BorderThickness, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontFamily="{Binding FontFamily, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontSize="{Binding FontSize, RelativeSource={RelativeSource AncestorType=UserControl}}"
        Text="{Binding TextBase, RelativeSource={RelativeSource AncestorType=UserControl}}"
        TextChanged="txtSearchBox_TextChanged" />

    <TextBlock
        x:Name="txt_HintBox"
        Margin="3,0,0,0"
        VerticalAlignment="Center"
        Background="Transparent"
        FontFamily="{Binding FontFamily, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontSize="{Binding FontSize, RelativeSource={RelativeSource AncestorType=UserControl}}"
        FontStyle="{Binding FontStyle, RelativeSource={RelativeSource AncestorType=UserControl}}"
        Foreground="{Binding ForegroundColorOverlay, RelativeSource={RelativeSource AncestorType=UserControl}}"
        IsHitTestVisible="False"
        Text="{Binding Hint, ElementName=TextBoxUserWindow}" />
    </Grid>
</UserControl>

This is the code-behind file of the user control:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace PasswordManager.Helpers.Resource_UserDefined
{
    public partial class TextBox_Hint : UserControl, INotifyPropertyChanged
    {
        public TextBox_Hint()
        {
            InitializeComponent();
        }

        public string TextBase
        {
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); OnPropertyChanged(); }
        }

        // Using a DependencyProperty as the backing store for TextBase. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty TextProperty = DependencyProperty.Register("TextBase", typeof(string), typeof(TextBox_Hint));

        public string Hint
        {
            get { return (string)GetValue(HintProperty); }
            set { SetValue(HintProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Hint. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty HintProperty = DependencyProperty.Register("Hint", typeof(string), typeof(TextBox_Hint), new PropertyMetadata(""));

        public Brush Background
        {
            get { return (Brush)GetValue(BackgroundProperty); }
            set { SetValue(BackgroundProperty, value); }
        }

        // Using a DependencyProperty as the backing store for background. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackgroundProperty = DependencyProperty.Register("Background", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.White));

        public Brush BorderColorBrush
        {
            get { return (Brush)GetValue(BorderColorBrushProperty); }
            set { SetValue(BorderColorBrushProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BorderColorBrush. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BorderColorBrushProperty = DependencyProperty.Register("BorderColorBrush", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.Black));

        public Thickness BorderThickness
        {
            get { return (Thickness)GetValue(BorderThicknessProperty); }
            set { SetValue(BorderThicknessProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BorderThickness. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BorderThicknessProperty = DependencyProperty.Register("BorderThickness", typeof(Thickness), typeof(TextBox_Hint), new PropertyMetadata(new Thickness(1,1,1,1)));

        public Brush ForegroundColorOverlay
        {
            get { return (Brush)GetValue(ForegroundColorOverlayProperty); }
            set { SetValue(ForegroundColorOverlayProperty, value); }
        }

        // Usando un DependencyProperty come memorizzazione per ForegroundColorOverlay
        public static readonly DependencyProperty ForegroundColorOverlayProperty = DependencyProperty.Register("ForegroundColorOverlay", typeof(Brush), typeof(TextBox_Hint), new PropertyMetadata(Brushes.Gray));

        public FontFamily FontFamily
        {
            get { return (FontFamily)GetValue(FontFamilyProperty); }
            set { SetValue(FontFamilyProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontFamily. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontFamilyProperty = DependencyProperty.Register("FontFamily", typeof(FontFamily), typeof(TextBox_Hint), new PropertyMetadata(new FontFamily("Arial")));

        public FontStyle FontStyle
        {
            get { return (FontStyle)GetValue(FontStyleProperty); }
            set { SetValue(FontStyleProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontStyle. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontStyleProperty = DependencyProperty.Register("FontStyle", typeof(FontStyle), typeof(TextBox_Hint), new PropertyMetadata(FontStyles.Normal));

        public Double FontSize
        {
            get { return (Double)GetValue(FontSizeProperty); }
            set { SetValue(FontSizeProperty, value); }
        }

        // Using a DependencyProperty as the backing store for FontSize. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty FontSizeProperty = DependencyProperty.Register("FontSize", typeof(Double), typeof(TextBox_Hint), new PropertyMetadata(20.0));

        private void txtSearchBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            if (string.IsNullOrEmpty(txtSearchBox.Text))
                txt_HintBox.Visibility = Visibility.Visible;
            else
                txt_HintBox.Visibility = Visibility.Hidden;
        }

        public event PropertyChangedEventHandler? PropertyChanged;

        protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

I use the user control like this:

<userControls:TextBox_Hint
x:Name="TextBox_Reame"
Height="40"
BorderColorBrush="Black"
BorderThickness="0,0,0,1"
FontFamily="{DynamicResource Abel}"
FontSize="20"
FontStyle="Italic"
ForegroundColorOverlay="Gray"
Hint="Inserisci Il Reame"
TextBase="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type userControls:TextBox_Hint}}, Path=TextBase}">
<userControls:TextBox_Hint.Background>
    <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
        <GradientStop Offset="0.0" Color="White" />
        <GradientStop Offset="0.5" Color="#FFE1FFE6" />
        <GradientStop Offset="1.0" Color="White" />
    </LinearGradientBrush>
</userControls:TextBox_Hint.Background>
  </userControls:TextBox_Hint>

This is the string property:

    private string _Reame;

    public string Reame
    {
        get { return _Reame; }
        set { _Reame = value; OnPropertyChanged(); }
    }

Now the problem start. I've tried 1000 times to try to fix the issues but with no response. My question is quite simple I think... how can I get the TextBase value (of the user control) directly into my code-behind of the window where I'm using it?

If I use TextBox_Reame.TextBase, I can perfectly get the value, but I want to use binding. I'm not interested in view model for this window because the low data values.

Thanks to everyone

• c#
• wpf
• binding
• user-controls
• code-behind

• So, how you tried? Have you checked How to: Create a Binding in Code? – emoacht Commented Mar 15 at 12:28
• As a note, it is pointless to implement INotifyPropertyChanged in a class with dependency properties. Those properties do already provide change notification. – Clemens Commented Mar 15 at 13:39
• The TextBase Binding looks like a failed attempt to bind the property to itself. What's the point? – Clemens Commented Mar 16 at 7:24

1 Answer 1

I'll support @Clemens . I also don't quite understand what you want to do and what doesn't work for you.

I'll assume that you have a ViewModel with a "public string Reame" property in the Data Context.

In that case, the "TextBox_Reame.TextBase" binding should be set to this property, not to itself.

    <userControls:TextBox_Hint
        x:Name="TextBox_Reame"
        Height="40"
        BorderColorBrush="Black"
        BorderThickness="0,0,0,1"
        FontFamily="{DynamicResource Abel}"
        FontSize="20"
        FontStyle="Italic"
        ForegroundColorOverlay="Gray"
        Hint="Inserisci Il Reame"
        TextBase="{Binding Reame}">
        <!--TextBase="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type userControls:TextBox_Hint}}, Path=TextBase}">-->
        <userControls:TextBox_Hint.Background>
            <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
                <GradientStop Offset="0.0" Color="White" />
                <GradientStop Offset="0.5" Color="#FFE1FFE6" />
                <GradientStop Offset="1.0" Color="White" />
            </LinearGradientBrush>
        </userControls:TextBox_Hint.Background>
    </userControls:TextBox_Hint>

I also recommend that you use Custom Control instead of UserControl:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace SOTopics2025.SO.user27828246.question79511053
{
    public class TextBox_Hint : TextBox
    {
        static TextBox_Hint()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(TextBox_Hint), new FrameworkPropertyMetadata(typeof(TextBox_Hint)));
        }

        public string Hint
        {
            get => (string)GetValue(HintProperty);
            set => SetValue(HintProperty, value);
        }

        // Using a DependencyProperty as the backing store for Hint. This enables animation, styling, binding, etc...
        public static readonly DependencyProperty HintProperty
            = DependencyProperty.Register(nameof(Hint),
                                          typeof(string),
                                          typeof(TextBox_Hint),
                                          new PropertyMetadata(string.Empty));

        public Brush HintForeground
        {
            get => (Brush)GetValue(HintForegroundProperty);
            set => SetValue(HintForegroundProperty, value);
        }

        // Usando un DependencyProperty come memorizzazione per ForegroundColorOverlay
        public static readonly DependencyProperty HintForegroundProperty
            = DependencyProperty.Register(nameof(HintForeground),
                                          typeof(Brush),
                                          typeof(TextBox_Hint),
                                          new PropertyMetadata(Brushes.Gray));

        public Visibility HintVisibility
        {
            get => (Visibility)GetValue(HintVisibilityProperty);
            private set => SetValue(HintVisibilityPropertyKey, value);
        }

        // Using a DependencyProperty as the backing store for Hint. This enables animation, styling, binding, etc...
        public static readonly DependencyPropertyKey HintVisibilityPropertyKey
            = DependencyProperty.RegisterReadOnly(nameof(HintVisibility),
                                          typeof(Visibility),
                                          typeof(TextBox_Hint),
                                          new PropertyMetadata(Visibility.Visible));
        public static readonly DependencyProperty HintVisibilityProperty = HintVisibilityPropertyKey.DependencyProperty;

        protected override void OnTextChanged(TextChangedEventArgs e)
        {
            base.OnTextChanged(e);
            HintVisibility = string.IsNullOrEmpty(Text) ? Visibility.Visible : Visibility.Collapsed;
        }
    }
}

Themes/Generic.xaml:

    <SolidColorBrush x:Key="TextBox_Hint.Static.Border" Color="#FFABAdB3"/>
    <SolidColorBrush x:Key="TextBox_Hint.MouseOver.Border" Color="#FF7EB4EA"/>
    <SolidColorBrush x:Key="TextBox_Hint.Focus.Border" Color="#FF569DE5"/>
    <Style TargetType="{x:Type custcont:TextBox_Hint}">
        <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
        <Setter Property="BorderBrush" Value="{StaticResource TextBox_Hint.Static.Border}"/>
        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="KeyboardNavigation.TabNavigation" Value="None"/>
        <Setter Property="HorizontalContentAlignment" Value="Left"/>
        <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
        <Setter Property="AllowDrop" Value="true"/>
        <Setter Property="ScrollViewer.PanningMode" Value="VerticalFirst"/>
        <Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type custcont:TextBox_Hint}">
                    <Border x:Name="border" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" SnapsToDevicePixels="True">
                        <Grid>
                            <ScrollViewer x:Name="PART_ContentHost" Focusable="false" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Hidden"/>
                            <TextBlock  x:Name="Hint_text" Text="{TemplateBinding Hint}" Foreground="{TemplateBinding HintForeground}"
                                        Visibility="{TemplateBinding HintVisibility}" IsHitTestVisible="False"/>
                        </Grid>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter Property="Opacity" TargetName="border" Value="0.56"/>
                        </Trigger>
                        <Trigger Property="IsMouseOver" Value="true">
                            <Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox_Hint.MouseOver.Border}"/>
                        </Trigger>
                        <Trigger Property="IsKeyboardFocused" Value="true">
                            <Setter Property="BorderBrush" TargetName="border" Value="{StaticResource TextBox_Hint.Focus.Border}"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <MultiTrigger>
                <MultiTrigger.Conditions>
                    <Condition Property="IsInactiveSelectionHighlightEnabled" Value="true"/>
                    <Condition Property="IsSelectionActive" Value="false"/>
                </MultiTrigger.Conditions>
                <Setter Property="SelectionBrush" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
            </MultiTrigger>
        </Style.Triggers>
    </Style>

Usage:

    <StackPanel>
        <FrameworkElement.DataContext>
            <local:SomeViewModel Reame="Some text"/>
        </FrameworkElement.DataContext>
        <local:TextBox_Hint Hint="Inserisci Il Reame" Text="{Binding Reame, UpdateSourceTrigger=PropertyChanged}"
                            Margin="10"/>
        <TextBlock Text="{Binding Reame}"/> <!-- For testing -->
    </StackPanel>