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Traduction
Anglais

Comment : implémenter un fournisseur d'extendeurs HelpLabel

Un fournisseur d'extendeurs est un composant qui fournit des propriétés à d'autres composants. Par exemple, le contrôle ToolTip est implémenté en tant que fournisseur d'extendeurs. Lorsque vous ajoutez un contrôle ToolTip à Form, une propriété ToolTip est ajoutée à la liste de propriétés de tous les autres contrôles sur Form.

L'exemple suivant montre comment générer un fournisseur d'extendeurs en créant le contrôle HelpLabel. Il présente l'implémentation de la méthode CanExtend et la propriété HelpText. La méthode CanExtend est utilisée par le Concepteur Windows Forms pour déterminer s'il faut étendre cette propriété à un contrôle donné. Le contrôle HelpLabel étend la propriété HelpText pour une utilisation avec les contrôles d'un formulaire. Le texte d'aide pour un contrôle s'affiche dans un panneau lorsque le contrôle a le focus.

Cet exemple inclut un concepteur imbriqué qui est décrit dans Comment : implémenter un concepteur pour un contrôle.

Il illustre les éléments suivants :

  • Le fournisseur d'extendeurs HelpLabel implémente IExtenderProvider.

  • Le contrôle HelpLabel utilise ProvidePropertyAttribute pour spécifier le nom de la propriété fournie ainsi que le type des composants qui peuvent recevoir la propriété.

  • HelpLabel est lui-même un contrôle Windows Forms et, par conséquent, dérive de Control.

  • La méthode CanExtend retourne true pour tous les contrôles, sauf HelpLabel (parce qu'il n'y a aucun intérêt à étendre une propriété sur elle-même).

  • HelpLabel possède une méthode nommée GetHelpText qui reçoit la propriété que HelpLabel met à la disposition d'autres contrôles. La méthode SetHelpText définit la valeur de la propriété.

    Remarque Remarque

    La propriété étendue est fournie par les méthodes GetHelpText et SetHelpText, et HelpLabel n'expose pas une propriété nommée HelpText.

La classe HostApp utilise le contrôle HelpLabel sur un formulaire.


      Option Strict On 
Option Explicit On  
Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.ComponentModel.Design
Imports System.Drawing
Imports System.Windows.Forms
Imports System.Windows.Forms.Design

Namespace Microsoft.Samples.WinForms.Vb.HelpLabel
    
    ' <doc> 
    ' <desc> 
    ' Help Label offers an extender property called 
    ' HelpText.  It monitors the active control 
    ' and displays the help text for the active control. 
    ' </desc> 
    ' </doc> 
    '

    <ProvideProperty("HelpText", GetType(Control)), Designer(GetType(HelpLabel.HelpLabelDesigner))> _
    Public Class HelpLabel
        Inherits Control
        Implements System.ComponentModel.IExtenderProvider
        ' <summary> 
        '    Required designer variable. 
        ' </summary> 
        Private components As System.ComponentModel.Container
        Private helpTexts As Hashtable
        Private activeControl As System.Windows.Forms.Control

        
        ' <doc> 
        ' <desc> 
        '      Creates a new help label object. 
        ' </desc> 
        ' </doc> 
        
        Public Sub New()
            
            ' Required for Windows Form designer support. 
            '
            InitializeComponent()
            helpTexts = New Hashtable
        End Sub 

        ' <summary> 
        '    Clean up any resources being used. 
        ' </summary> 
        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If disposing Then 
                If components IsNot Nothing Then
                    components.Dispose()
                End If 
            End If 
            MyBase.Dispose(disposing)
        End Sub 

        ' <summary> 
        '    Required method for designer support. Do not modify 
        '    the contents of this method with the code editor. 
        ' </summary> 
        Private Sub InitializeComponent()
            Me.components = New System.ComponentModel.Container
            Me.BackColor = System.Drawing.SystemColors.Info
            Me.ForeColor = System.Drawing.SystemColors.InfoText
            Me.TabStop = False 
        End Sub 
        
        ' <doc> 
        ' <desc> 
        '      Overrides the text property of Control.  This label ignores 
        '      the text property, so we add additional attributes here so the 
        '      property does not show up in the Properties window and is not 
        '      persisted. 
        ' </desc> 
        ' </doc> 
        '
        <Browsable(False), _
        EditorBrowsable(EditorBrowsableState.Never), _
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)> _
        Public Overrides Property [Text]() As String 
            Get 
                Return MyBase.Text
            End Get 
            Set(ByVal Value As String)
                MyBase.Text = Value
            End Set 
        End Property 


        
        ' <doc> 
        ' <desc> 
        '      This implements the IExtenderProvider.CanExtend method.  The 
        '      help label provides an extender property, and the design-time 
        '      framework will call this method once for each component to determine 
        '      if we are interested in providing our extended properties for the 
        '      component.  We return true here if the object is a control and is 
        '      not a HelpLabel (because it would not be meaningful to add this property to 
        '      ourselves). 
        ' </desc> 
        ' </doc> 
        
        Function CanExtend(ByVal target As Object) As Boolean Implements IExtenderProvider.CanExtend
            If TypeOf target Is Control And Not TypeOf target Is HelpLabel Then 

                Return True 
            End If 
            Return False 
        End Function 

        
        ' <doc> 
        ' <desc> 
        '      This is the extended property for the HelpText property.  Extended 
        '      properties are actual methods because they take an additional parameter 
        '      that is the object or control to provide the property for. 
        ' </desc> 
        ' </doc> 
        '
        <DefaultValue("")> _
        Public Function GetHelpText(ByVal ctrl As Control) As String 
            Dim myText As String = CStr(helpTexts(ctrl))
            If myText Is Nothing Then
                myText = String.Empty
            End If 
            Return myText
        End Function 

        
        ' <doc> 
        ' <desc> 
        '      This is the extended property for the HelpText property. 
        ' </desc> 
        ' </doc> 
        
        Public Sub SetHelpText(ByVal ctrl As Control, ByVal value As String)
            If value Is Nothing Then
                value = String.Empty
            End If 

            If value.Length = 0 Then
                helpTexts.Remove(ctrl)

                RemoveHandler ctrl.Enter, AddressOf OnControlEnter
                RemoveHandler ctrl.Leave, AddressOf OnControlLeave
            Else
                helpTexts(ctrl) = value
                AddHandler ctrl.Enter, AddressOf OnControlEnter
                AddHandler ctrl.Leave, AddressOf OnControlLeave
            End If 

            If ctrl Is activeControl Then
                Invalidate()
            End If 
        End Sub 

        
        ' <doc> 
        ' <desc> 
        '      This is an event handler that responds to the OnControlEnter 
        '      event.  We attach this to each control we are providing help 
        '      text for. 
        ' </desc> 
        ' </doc> 
        
        Private Sub OnControlEnter(ByVal sender As Object, ByVal e As EventArgs)
            activeControl = CType(sender, Control)
            Invalidate()
        End Sub 

        
        ' <doc> 
        ' <desc> 
        '      This is an event handler that responds to the OnControlLeave 
        '      event.  We attach this to each control we are providing help 
        '      text for. 
        ' </desc> 
        ' </doc> 
        
        Private Sub OnControlLeave(ByVal sender As Object, ByVal e As EventArgs)
            If sender Is activeControl Then
                activeControl = Nothing
                Invalidate()
            End If 
        End Sub 

        
        ' <doc> 
        ' <desc> 
        '      Overrides Control.OnPaint.  Here we draw our 
        '      label. 
        ' </desc> 
        ' </doc> 
        
        Protected Overrides Sub OnPaint(ByVal pe As PaintEventArgs)
            ' Let the base draw.  This will cover our back 
            ' color and set any image that the user has 
            ' provided. 
            
            MyBase.OnPaint(pe)

            ' Draw a rectangle around the control. 
            
            Dim rect As Rectangle = ClientRectangle

            Dim borderPen As New Pen(ForeColor)
            pe.Graphics.DrawRectangle(borderPen, rect)
            borderPen.Dispose()

            ' Finally, draw the text over the top of the 
            ' rectangle. 
            
            If (activeControl IsNot Nothing) Then 
                Dim myText As String = CStr(helpTexts(activeControl))
                If (myText IsNot Nothing) And myText.Length > 0 Then
                    rect.Inflate(-2, -2)
                    Dim brush As New SolidBrush(ForeColor)
                    pe.Graphics.DrawString(myText, Font, brush, RectangleF.op_Implicit(rect))
                    brush.Dispose()
                End If 
            End If 
        End Sub 


        ' <doc> 
        ' <desc> 
        '     Returns true if backColor should be persisted in code gen.  We 
        '      override this because we change the default back color. 
        ' </desc> 
        ' <retvalue> 
        '     true if the backColor should be persisted. 
        ' </retvalue> 
        ' </doc> 
        
        Public Function ShouldSerializeBackColor() As Boolean 
            Return Not BackColor.Equals(SystemColors.Info)
        End Function 


        ' <doc> 
        ' <desc> 
        '     Returns true if foreColor should be persisted in code gen.  We 
        '      override this because we change the default foreground color. 
        ' </desc> 
        ' <retvalue> 
        '     true if foreColor should be persisted. 
        ' </retvalue> 
        ' </doc> 
        
        Public Function ShouldSerializeForeColor() As Boolean 
            Return Not ForeColor.Equals(SystemColors.InfoText)
        End Function 

        
        ' <doc> 
        ' <desc> 
        '      This is a designer for the HelpLabel.  This designer provides 
        '      design time feedback for the label.  The help label responds 
        '      to changes in the active control, but these events do not 
        '      occur at design time.  In order to provide some usable feedback 
        '      that the control is working the right way, this designer listens 
        '      to selection change events and uses those events to trigger active 
        '      control changes. 
        ' </desc> 
        ' </doc> 
        '
        <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
        Public Class HelpLabelDesigner
            Inherits System.Windows.Forms.Design.ControlDesigner

            Private _trackSelection As Boolean = True 

            ' <summary> 
            ' This property is added to the control's set of properties in the method 
            ' PreFilterProperties below.  Note that on designers, properties that are 
            ' explictly declared by TypeDescriptor.CreateProperty can be declared as 
            ' private on the designer.  This helps to keep the designer's public 
            ' object model clean. 
            ' </summary>
            <DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)> _
            Private Property TrackSelection() As Boolean 
                Get 
                    Return _trackSelection
                End Get 
                Set(ByVal Value As Boolean)
                    _trackSelection = Value
                    If _trackSelection Then 
                        Dim ss As ISelectionService = CType(GetService(GetType(ISelectionService)), ISelectionService)
                        If (ss IsNot Nothing) Then
                            UpdateHelpLabelSelection(ss)
                        End If 
                    Else 
                        Dim helpLabel As HelpLabel = CType(Control, HelpLabel)
                        If (helpLabel.activeControl IsNot Nothing) Then
                            helpLabel.activeControl = Nothing
                            helpLabel.Invalidate()
                        End If 
                    End If 
                End Set 
            End Property 

            Public Overrides ReadOnly Property Verbs() As DesignerVerbCollection
                Get 
                    Dim myVerbs() As DesignerVerb = {New DesignerVerb("Sample Verb", AddressOf OnSampleVerb)}
                    Return New DesignerVerbCollection(myVerbs)
                End Get 
            End Property 

            
            ' <doc> 
            ' <desc> 
            '      Overrides Dispose.  Here we remove our handler for the selection changed 
            '      event.  With designers, it is critical that they clean up any events they 
            '      have attached.  Otherwise, during the course of an editing session many 
            '      designers might get created and never destroyed. 
            ' </desc> 
            ' </doc> 
            
            Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
                If disposing Then 
                    Dim ss As ISelectionService = CType(GetService(GetType(ISelectionService)), ISelectionService)
                    If (ss IsNot Nothing) Then 
                        RemoveHandler ss.SelectionChanged, AddressOf OnSelectionChanged
                    End If 
                End If 
                MyBase.Dispose(disposing)
            End Sub 

            
            ' <doc> 
            ' <desc> 
            '       Overrides initialize.  Here we add an event handler to the selection service. 
            '      Notice that we are very careful not to assume that the selection service is 
            '      available.  It is entirely optional that a service is available and you should 
            '      always degrade gracefully if a service cannot be found. 
            ' </desc> 
            ' </doc> 
            
            Public Overrides Sub Initialize(ByVal component As IComponent)
                MyBase.Initialize(component)

                Dim ss As ISelectionService = CType(GetService(GetType(ISelectionService)), ISelectionService)
                If (ss IsNot Nothing) Then 
                    AddHandler ss.SelectionChanged, AddressOf OnSelectionChanged
                End If 
            End Sub 

            Private Sub OnSampleVerb(ByVal sender As Object, ByVal e As EventArgs)
                MessageBox.Show("You have just invoked a sample verb.  Normally, this would do something interesting.")
            End Sub 

            
            ' <doc> 
            ' <desc> 
            '      The handler for the selection change event.  Here we update the active control within 
            '      the help label. 
            ' </desc> 
            ' </doc> 
            
            Private Sub OnSelectionChanged(ByVal sender As Object, ByVal e As EventArgs)
                If _trackSelection Then 
                    Dim ss As ISelectionService = CType(sender, ISelectionService)
                    UpdateHelpLabelSelection(ss)
                End If 
            End Sub 

            Protected Overrides Sub PreFilterProperties(ByVal properties As IDictionary)
                ' Always call base first in PreFilter* methods, and last in PostFilter* 
                ' methods. 
                MyBase.PreFilterProperties(properties)

                ' We add a design-time property called TrackSelection that is used to track 
                ' the active selection.  If the user sets this to true (the default), then 
                ' we will listen to selection change events and update the control's active 
                ' control to point to the current primary selection.
                properties("TrackSelection") = TypeDescriptor.CreateProperty( _
                   Me.GetType(), _
                   "TrackSelection", _
                   GetType(Boolean), _
                   New Attribute() {CategoryAttribute.Design})
            End Sub 

            ' <summary> 
            ' This is a helper method that, given a selection service, will update the active control 
            ' of the help label with the currently active selection. 
            ' </summary> 
            ' <param name="ss"></param> 
            Private Sub UpdateHelpLabelSelection(ByVal ss As ISelectionService)
                Dim c As Control = CType(ss.PrimarySelection, Control)
                Dim helpLabel As HelpLabel = CType(Control, HelpLabel)
                If (c IsNot Nothing) Then
                    helpLabel.activeControl = c
                    helpLabel.Invalidate()
                Else 
                    If (helpLabel.activeControl IsNot Nothing) Then
                        helpLabel.activeControl = Nothing
                        helpLabel.Invalidate()
                    End If 
                End If 
            End Sub 

            Public Sub New()

            End Sub 
        End Class 

    End Class 
End Namespace

      namespace Microsoft.Samples.WinForms.Cs.HelpLabel 
{
	using System;
	using System.Collections;
	using System.ComponentModel;
	using System.ComponentModel.Design;
	using System.Drawing;
	using System.Windows.Forms;
	using System.Windows.Forms.Design;

	// 
	// <doc> 
	// <desc> 
	// Help Label offers an extender property called 
	// "HelpText".  It monitors the active control
	// and displays the help text for the active control. 
	// </desc> 
	// </doc> 
	//
	[
	ProvideProperty("HelpText",typeof(Control)),
	Designer(typeof(HelpLabel.HelpLabelDesigner))
	]
	public class HelpLabel : Control, System.ComponentModel.IExtenderProvider 
	{
		/// <summary> 
		///    Required designer variable. 
		/// </summary> 
		private System.ComponentModel.Container components;
		private Hashtable helpTexts;
		private System.Windows.Forms.Control activeControl;

		// 
		// <doc> 
		// <desc> 
		//      Creates a new help label object. 
		// </desc> 
		// </doc> 
		// 
		public HelpLabel() 
		{
			// 
			// Required for Windows Form Designer support 
			//
			InitializeComponent();

			helpTexts = new Hashtable();
		}

		/// <summary> 
		///    Clean up any resources being used. 
		/// </summary> 
		protected override void Dispose(bool disposing) 
		{
			if (disposing) 
			{
				components.Dispose();
			}
			base.Dispose(disposing);
		}

		/// <summary> 
		///    Required method for Designer support - do not modify 
		///    the contents of this method with the code editor. 
		/// </summary> 
		private void InitializeComponent() 
		{
			this.components = new System.ComponentModel.Container ();
			this.BackColor = System.Drawing.SystemColors.Info;
			this.ForeColor = System.Drawing.SystemColors.InfoText;
			this.TabStop = false;
		}

		// 
		// <doc> 
		// <desc> 
		//      Overrides the text property of Control.  This label ignores 
		//      the text property, so we add additional attributes here so the 
		//      property does not show up in the properties window and is not 
		//      persisted. 
		// </desc> 
		// </doc> 
		//
		[
		Browsable(false),
		EditorBrowsable(EditorBrowsableState.Never),
		DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)
		]
		public override string Text 
		{
			get 
			{
				return base.Text;
			}
			set 
			{
				base.Text = value;
			}
		}

		// 
		// <doc> 
		// <desc> 
		//      This implements the IExtenderProvider.CanExtend method.  The 
		//      help label provides an extender property, and the design time 
		//      framework will call this method once for each component to determine 
		//      if we are interested in providing our extended properties for the 
		//      component.  We return true here if the object is a control and is 
		//      not a HelpLabel (since it would be silly to add this property to 
		//      ourselves). 
		// </desc> 
		// </doc> 
		// 
		bool IExtenderProvider.CanExtend(object target) 
		{
			if (target is Control &&
				!(target is HelpLabel)) 
			{

				return true;
			}
			return false;
		}

		// 
		// <doc> 
		// <desc> 
		//      This is the extended property for the HelpText property.  Extended 
		//      properties are actual methods because they take an additional parameter 
		//      that is the object or control to provide the property for. 
		// </desc> 
		// </doc> 
		//
		[
		DefaultValue(""),
		]
		public string GetHelpText(Control control) 
		{
			string text = (string)helpTexts[control];
			if (text == null) 
			{
				text = string.Empty;
			}
			return text;
		}

		// 
		// <doc> 
		// <desc> 
		//      This is an event handler that responds to the OnControlEnter 
		//      event.  We attach this to each control we are providing help 
		//      text for. 
		// </desc> 
		// </doc> 
		// 
		private void OnControlEnter(object sender, EventArgs e) 
		{
			activeControl = (Control)sender;
			Invalidate();
		}

		// 
		// <doc> 
		// <desc> 
		//      This is an event handler that responds to the OnControlLeave 
		//      event.  We attach this to each control we are providing help 
		//      text for. 
		// </desc> 
		// </doc> 
		// 
		private void OnControlLeave(object sender, EventArgs e) 
		{
			if (sender == activeControl) 
			{
				activeControl = null;
				Invalidate();
			}
		}

		// 
		// <doc> 
		// <desc> 
		//      This is the extended property for the HelpText property. 
		// </desc> 
		// </doc> 
		// 
		public void SetHelpText(Control control, string value) 
		{
			if (value == null) 
			{
				value = string.Empty;
			}

			if (value.Length == 0) 
			{
				helpTexts.Remove(control);

				control.Enter -= new EventHandler(OnControlEnter);
				control.Leave -= new EventHandler(OnControlLeave);
			}
			else 
			{
				helpTexts[control] = value;

				control.Enter += new EventHandler(OnControlEnter);
				control.Leave += new EventHandler(OnControlLeave);
			}

			if (control == activeControl) 
			{
				Invalidate();
			}
		}

		// 
		// <doc> 
		// <desc> 
		//      Overrides Control.OnPaint.  Here we draw our 
		//      label. 
		// </desc> 
		// </doc> 
		// 
		protected override void OnPaint(PaintEventArgs pe) 
		{

			// Let the base draw.  This will cover our back 
			// color and set any image that the user may have 
			// provided. 
			// 
			base.OnPaint(pe);

			// Draw a rectangle around our control. 
			//
			Rectangle rect = ClientRectangle;

			Pen borderPen = new Pen(ForeColor);
			pe.Graphics.DrawRectangle(borderPen, rect);
			borderPen.Dispose();

			// Finally, draw the text over the top of the 
			// rectangle. 
			// 
			if (activeControl != null) 
			{
				string text = (string)helpTexts[activeControl];
				if (text != null && text.Length > 0) 
				{
					rect.Inflate(-2, -2);
					Brush brush = new SolidBrush(ForeColor);
					pe.Graphics.DrawString(text, Font, brush, rect);
					brush.Dispose();
				}
			}
		}

		// <doc> 
		// <desc> 
		//     Returns true if the backColor should be persisted in code gen.  We 
		//      override this because we change the default back color. 
		// </desc> 
		// <retvalue> 
		//     true if the backColor should be persisted. 
		// </retvalue> 
		// </doc> 
		// 
		public bool ShouldSerializeBackColor() 
		{
			return(!BackColor.Equals(SystemColors.Info));
		}

		// <doc> 
		// <desc> 
		//     Returns true if the foreColor should be persisted in code gen.  We 
		//      override this because we change the default foreground color. 
		// </desc> 
		// <retvalue> 
		//     true if the foreColor should be persisted. 
		// </retvalue> 
		// </doc> 
		// 
		public bool ShouldSerializeForeColor() 
		{
			return(!ForeColor.Equals(SystemColors.InfoText));
		}

		// 
		// <doc> 
		// <desc> 
		//      This is a designer for the HelpLabel.  This designer provides 
		//      design time feedback for the label.  The help label responds 
		//      to changes in the active control, but these events do not 
		//      occur at design time.  In order to provide some usable feedback 
		//      that the control is working the right way, this designer listens 
		//      to selection change events and uses those events to trigger active 
		//      control changes. 
		// </desc> 
		// </doc> 
		//
        [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
		public class HelpLabelDesigner : System.Windows.Forms.Design.ControlDesigner 
		{

			private bool trackSelection = true;

			/// <summary> 
			/// This property is added to the control's set of properties in the method 
			/// PreFilterProperties below.  Note that on designers, properties that are 
			/// explictly declared by TypeDescriptor.CreateProperty can be declared as 
			/// private on the designer.  This helps to keep the designer's publi 
			/// object model clean. 
			/// </summary>
            [DesignerSerializationVisibility( DesignerSerializationVisibility.Hidden )]
			private bool TrackSelection
			{
				get
				{
					return trackSelection;
				}
				set
				{
					trackSelection = value;
					if (trackSelection)
					{
						ISelectionService ss = (ISelectionService)GetService(typeof(ISelectionService));
						if (ss != null)
						{
							UpdateHelpLabelSelection(ss);
						}
					}
					else
					{
						HelpLabel helpLabel = (HelpLabel)Control;
						if (helpLabel.activeControl != null)
						{
							helpLabel.activeControl = null;
							helpLabel.Invalidate();
						}
					}
				}
			}

			public override DesignerVerbCollection Verbs
			{
				get
				{
					DesignerVerb[] verbs = new DesignerVerb[] {
																  new DesignerVerb("Sample Verb", new EventHandler(OnSampleVerb))
															  };
					return new DesignerVerbCollection(verbs);
				}
			}

			// 
			// <doc> 
			// <desc> 
			//      Overrides Dispose.  Here we remove our handler for the selection changed 
			//      event.  With designers, it is critical that they clean up any events they 
			//      have attached.  Otherwise, during the course of an editing session many 
			//      designers may get created and never destroyed. 
			// </desc> 
			// </doc> 
			// 
			protected override void Dispose(bool disposing) 
			{
				if (disposing) 
				{
					ISelectionService ss = (ISelectionService)GetService(typeof(ISelectionService));
					if (ss != null) 
					{
						ss.SelectionChanged -= new EventHandler(OnSelectionChanged);
					}
				}

				base.Dispose(disposing);
			}

			// 
			// <doc> 
			// <desc> 
			//       Overrides initialize.  Here we add an event handler to the selection service. 
			//      Notice that we are very careful not to assume that the selection service is 
			//      available.  It is entirely optional that a service is available and you should 
			//      always degrade gracefully if a service could not be found. 
			// </desc> 
			// </doc> 
			// 
			public override void Initialize(IComponent component) 
			{
				base.Initialize(component);

				ISelectionService ss = (ISelectionService)GetService(typeof(ISelectionService));
				if (ss != null) 
				{
					ss.SelectionChanged += new EventHandler(OnSelectionChanged);
				}
			}

			private void OnSampleVerb(object sender, EventArgs e)
			{
				MessageBox.Show("You have just invoked a sample verb.  Normally, this would do something interesting.");
			}

			// 
			// <doc> 
			// <desc> 
			//      Our handler for the selection change event.  Here we update the active control within 
			//      the help label. 
			// </desc> 
			// </doc> 
			// 
			private void OnSelectionChanged(object sender, EventArgs e) 
			{
				if (trackSelection)
				{
					ISelectionService ss = (ISelectionService)sender;
					UpdateHelpLabelSelection(ss);
				}
			}

			protected override void PreFilterProperties(IDictionary properties)
			{
				// Always call base first in PreFilter* methods, and last in PostFilter* 
				// methods. 
				base.PreFilterProperties(properties);

				// We add a design-time property called "TrackSelection" that is used to track
				// the active selection.  If the user sets this to true (the default), then 
				// we will listen to selection change events and update the control's active 
				// control to point to the current primary selection.
				properties["TrackSelection"] = TypeDescriptor.CreateProperty(
					this.GetType(),        // the type this property is defined on 
					"TrackSelection",    // the name of the property 
					typeof(bool),        // the type of the property 
					new Attribute[] {CategoryAttribute.Design});    // attributes
			}

			/// <summary> 
			/// This is a helper method that, given a selection service, will update the active control 
			/// of our help label with the currently active selection. 
			/// </summary> 
			/// <param name="ss"></param>
			private void UpdateHelpLabelSelection(ISelectionService ss)
			{
				Control c = ss.PrimarySelection as Control;
				HelpLabel helpLabel = (HelpLabel)Control;
				if (c != null)
				{
					helpLabel.activeControl = c;
					helpLabel.Invalidate();
				}
				else
				{
					if (helpLabel.activeControl != null)
					{
						helpLabel.activeControl = null;
						helpLabel.Invalidate();
					}
				}
			}
		}
	}
}

      Imports System
Imports System.ComponentModel
Imports System.Drawing
Imports System.Windows.Forms


Public Class HostApp
   Inherits System.Windows.Forms.Form
    ' <summary> 
    '    Required designer variable. 
    ' </summary> 
   Private components As System.ComponentModel.Container
   Private label1 As System.Windows.Forms.Label
   Private textBox1 As System.Windows.Forms.TextBox
   Private button1 As System.Windows.Forms.Button
    Private helpLabel1 As Microsoft.Samples.WinForms.Vb.HelpLabel.HelpLabel


   Public Sub New()
      
      ' Required for Windows Form Designer support 
      '
      InitializeComponent()
    End Sub 


    ' <summary> 
    '    Required method for Designer support - do not modify 
    '    the contents of this method with the code editor. 
    ' </summary> 
    Private Sub InitializeComponent()
        Me.components = New System.ComponentModel.Container
        Me.label1 = New System.Windows.Forms.Label
        Me.button1 = New System.Windows.Forms.Button
        Me.textBox1 = New System.Windows.Forms.TextBox
        Me.helpLabel1 = New Microsoft.Samples.WinForms.Vb.HelpLabel.HelpLabel

        label1.Location = New System.Drawing.Point(16, 16)
        label1.Text = "Name:"
        label1.Size = New System.Drawing.Size(56, 24)
        label1.TabIndex = 3

        helpLabel1.Dock = System.Windows.Forms.DockStyle.Bottom
        helpLabel1.Size = New System.Drawing.Size(448, 40)
        helpLabel1.TabIndex = 0
        helpLabel1.Location = New System.Drawing.Point(0, 117)

        button1.Anchor = AnchorStyles.Right Or AnchorStyles.Bottom
        button1.Size = New System.Drawing.Size(104, 40)
        button1.TabIndex = 1
        helpLabel1.SetHelpText(button1, "This is the Save Button. Press the Save Button to save your work.")
        button1.Text = "&Save"
        button1.Location = New System.Drawing.Point(336, 56)

        Me.Text = "Control Example" 
        Me.ClientSize = New System.Drawing.Size(448, 157)

        textBox1.Anchor = AnchorStyles.Left Or AnchorStyles.Right Or AnchorStyles.Top
        textBox1.Location = New System.Drawing.Point(80, 16)
        textBox1.Text = "<Name>"
        helpLabel1.SetHelpText(textBox1, "This is the name field. Please enter your name here.")
        textBox1.TabIndex = 2
        textBox1.Size = New System.Drawing.Size(360, 20)

        Me.Controls.Add(label1)
        Me.Controls.Add(textBox1)
        Me.Controls.Add(button1)
        Me.Controls.Add(helpLabel1)
    End Sub 



    ' <summary> 
    ' The main entry point for the application. 
    ' </summary>
    <STAThread()> _
              Public Shared Sub Main(ByVal args() As String)
        Application.Run(New HostApp)
    End Sub 
End Class

      namespace Microsoft.Samples.WinForms.Cs.HostApp 
{
	using System;
	using System.ComponentModel;
	using System.Drawing;
	using System.Windows.Forms;
	using Microsoft.Samples.WinForms.Cs.HelpLabel;

	public class HostApp : System.Windows.Forms.Form 
	{
		/// <summary> 
		///    Required designer variable. 
		/// </summary> 
		private System.ComponentModel.Container components;
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.TextBox textBox1;
		private System.Windows.Forms.Button button1;
		private Microsoft.Samples.WinForms.Cs.HelpLabel.HelpLabel helpLabel1;

		public HostApp() 
		{
			// 
			// Required for Windows Form Designer support 
			//
			InitializeComponent();

		}

		/// <summary> 
		///    Clean up any resources being used. 
		/// </summary> 
		protected override void Dispose(bool disposing) 
		{
			if (disposing) 
			{
				components.Dispose();
			}
			base.Dispose(disposing);
		}

		/// <summary> 
		///    Required method for Designer support - do not modify 
		///    the contents of this method with the code editor. 
		/// </summary> 
		private void InitializeComponent() 
		{
			this.components = new System.ComponentModel.Container();
			this.label1 = new System.Windows.Forms.Label();
			this.button1 = new System.Windows.Forms.Button();
			this.textBox1 = new System.Windows.Forms.TextBox();
			this.helpLabel1 = new Microsoft.Samples.WinForms.Cs.HelpLabel.HelpLabel();

			label1.Location = new System.Drawing.Point(16, 16);
			label1.Text = "Name:";
			label1.Size = new System.Drawing.Size(56, 24);
			label1.TabIndex = 3;

			helpLabel1.Dock = System.Windows.Forms.DockStyle.Bottom;
			helpLabel1.Size = new System.Drawing.Size(448, 40);
			helpLabel1.TabIndex = 0;
			helpLabel1.Location = new System.Drawing.Point(0, 117);

			button1.Anchor = AnchorStyles.Right | AnchorStyles.Bottom;
			button1.Size = new System.Drawing.Size(104, 40);
			button1.TabIndex = 1;
			helpLabel1.SetHelpText(button1, "This is the Save Button. Press the Save Button to save your work.");
			button1.Text = "&Save";
			button1.Location = new System.Drawing.Point(336, 56);

			this.Text = "Control Example";
			this.ClientSize = new System.Drawing.Size(448, 157);

			textBox1.Anchor = AnchorStyles.Left| AnchorStyles.Right | AnchorStyles.Top;
			textBox1.Location = new System.Drawing.Point(80, 16);
			textBox1.Text = "<Name>";
			helpLabel1.SetHelpText(textBox1, "This is the name field. Please enter your name here.");
			textBox1.TabIndex = 2;
			textBox1.Size = new System.Drawing.Size(360, 20);

			this.Controls.Add(label1);
			this.Controls.Add(textBox1);
			this.Controls.Add(button1);
			this.Controls.Add(helpLabel1);
		}

		/// <summary> 
		/// The main entry point for the application. 
		/// </summary>
		[STAThread]
		public static void Main(string[] args) 
		{
			Application.Run(new HostApp());
		}

	}
}
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