' Follow steps 1a or 1b and then 2 to use this custom control in a XAML file.
'
' Step 1a) Using this custom control in a XAML file that exists in the current project.
' Add this XmlNamespace attribute to the root element of the markup file where it is 
' to be used:
'
'     xmlns:MyNamespace="clr-namespace:EgtWPFLib5"
'
'
' Step 1b) Using this custom control in a XAML file that exists in a different project.
' Add this XmlNamespace attribute to the root element of the markup file where it is 
' to be used:
'
'     xmlns:MyNamespace="clr-namespace:EgtWPFLib5;assembly=EgtWPFLib5"
'
' You will also need to add a project reference from the project where the XAML file lives
' to this project and Rebuild to avoid compilation errors:
'
'     Right click on the target project in the Solution Explorer and
'     "Add Reference"->"Projects"->[Browse to and select this project]
'
'
' Step 2)
' Go ahead and use your control in the XAML file. Note that Intellisense in the
' XML editor does not currently work on custom controls and its child elements.
'
'     <MyNamespace:EgtTextBox/>
'

Imports System.Windows.Controls.Primitives
Imports System.ComponentModel

Public Class EgtTextBox
   Inherits System.Windows.Controls.TextBox

   ' Proprietà che permette di impostare l'altezza della TitleBar
   Public Shared ReadOnly ExplicitUpdateSourceProperty As DependencyProperty = DependencyProperty.Register("ExplicitUpdateSource", GetType(UpdateSourceType), GetType(EgtTextBox), New PropertyMetadata(UpdateSourceType.Null))
   Public Property ExplicitUpdateSource() As UpdateSourceType
      Get
         Return DirectCast(GetValue(ExplicitUpdateSourceProperty), UpdateSourceType)
      End Get
      Set(ByVal value As UpdateSourceType)
         SetValue(ExplicitUpdateSourceProperty, value)
      End Set
   End Property

   Public Shared ReadOnly IsExplicitFocusedProperty As DependencyProperty = DependencyProperty.Register("IsExplicitFocused", GetType(Boolean), GetType(EgtTextBox), New UIPropertyMetadata(False, AddressOf OnIsFocusedPropertyChanged))
   Public Property IsExplicitFocused() As Boolean
      Get
         Return CBool(GetValue(IsExplicitFocusedProperty))
      End Get
      Set(ByVal value As Boolean)
         Me.Focus()
         SetValue(IsExplicitFocusedProperty, value)
      End Set
   End Property

   Public Enum UpdateSourceType As Integer
      Null = 0
      PropertyChanged = 1
      EnterKeyPress = 2
   End Enum

   Shared Sub New()
      'This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class.
      'This style is defined in themes\generic.xaml
      DefaultStyleKeyProperty.OverrideMetadata(GetType(EgtTextBox), New FrameworkPropertyMetadata(GetType(EgtTextBox)))
   End Sub

   Private Shared Sub OnIsFocusedPropertyChanged(d As DependencyObject, e As DependencyPropertyChangedEventArgs)
      Dim uie = DirectCast(d, UIElement)
      uie.Focus()
   End Sub

   Private Sub EgtTextBox_PreviewKeyDown(sender As Object, e As System.Windows.Input.KeyEventArgs) Handles Me.PreviewKeyDown
      If e.Key = Key.Enter Then
         If ExplicitUpdateSource = UpdateSourceType.EnterKeyPress Then
            Me.GetBindingExpression(TextBox.TextProperty).UpdateSource()
         End If
         Keyboard.ClearFocus()
      End If
   End Sub

   Private Sub EgtTextBox_TextChanged(sender As Object, e As System.Windows.Controls.TextChangedEventArgs) Handles Me.TextChanged
      If ExplicitUpdateSource = UpdateSourceType.PropertyChanged Then
         Me.GetBindingExpression(TextBox.TextProperty).UpdateSource()
      End If
   End Sub

   Private Sub ExplicitBindingTextBox_Loaded(sender As Object, e As RoutedEventArgs)
      Dim textBox As TextBox = TryCast(sender, TextBox)

      If TryCast(textBox.DataContext, INotifyPropertyChanged) Is Nothing Then
         Throw New InvalidOperationException("...")
      End If

      AddHandler TryCast(textBox.DataContext, INotifyPropertyChanged).PropertyChanged, AddressOf ViewModel_PropertyChanged
   End Sub

   Private Sub ViewModel_PropertyChanged(sender As Object, e As System.ComponentModel.PropertyChangedEventArgs)
      If ExplicitUpdateSource = UpdateSourceType.PropertyChanged Or ExplicitUpdateSource = UpdateSourceType.EnterKeyPress Then
         Me.GetBindingExpression(TextBox.TextProperty).UpdateTarget()
      End If
   End Sub

End Class