Enable event visibility for a child control of an usercontrol?

Question

Introduction

I have a Class that inherits from UserControl, inside this class I expose a child TextBox control:

Public NotInheritable Class MyUserControl: Inherits UserControl

...

    ''' <summary>
    ''' Gets the inner TextBox of this user control container.
    ''' </summary>
    <Browsable(True),
    EditorBrowsable(EditorBrowsableState.Always),
    DesignerSerializationVisibility(DesignerSerializationVisibility.Content)>
    <Description("The textbox control.")>
    Public ReadOnly Property TextBox As TextBox
        Get
            Return Me.textbox1
        End Get
    End Property

    <Browsable(False),
    EditorBrowsable(EditorBrowsableState.Advanced),
    DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)>
    Private WithEvents textbox1 As New TextBox With {...}

    Public Sub New()
        ...
        Dim container As New ContainerControl
        container.Controls.Add(Me.textbox1)
        Me.Controls.Add(container)
        ...
    End Sub

    ...

End Class

---

Problem

I just would like to be able to use the Handles statement at design time to let IntelliSense list that child TextBox events in the same way that we can use this feature to list and suscribe to the events of a default TextBox like in this example:

But when I try the same above with my user-contorl, the Handles statement does not recognize the child TextBox neither its events because the TextBox property seems not to be visible in that way, but note that I set the visibility of that member as Public and it is a Withevents member as I shown above in the introduction.

On the other hand, the TextBox property of my user-control is accesible manually, I can type the property name and the event name so this event-handler below will compile and works ok:

Private Sub MyUserControl_TextBox_TextChanged(sender As Object, e As EventArgs) _
Handles MyUserControl.TextBox.TextChanged

End Sub

The problem is that with that event-handler added into my source-code, when I return to the Visual GUI Builder of Visual Studio it throws this error:

So I cannot acces the Visual Builder until I remove the event-handler that is handling the child TextBox of my user-control.

The most weird thing is that as I said I cannot list the events using the Handles statement neither manually suscribe to them because it throws that error, but the events are accesible inside the control's property grid of the visual builder and if I double-click on an event name it generates the event-handler (that I cannot use as I explained), this is just ridiculous:

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Question

I'm doing something wrong?, how to fix that visual builder Error?

The most important thing, how I could use the Handles statement as normally for the child textbox control of my user-control?.

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Answer requisites

To easy solve the problem about the Handles statement and also about the Visual Builder I know that I just could add an additional reference to the child textbox of my user-control in this way:

Private WithEvents tb As TextBox = MyUserControlInstance.TextBox

Private Sub tb_TextChanged(sender As Object, e As EventArgs) _
Handles tb.TextChanged

End Sub

Or else I could expose the events of that child textbox from the "top-level" of my UserControl class, but that will be a nightmare of code-writting because I don't know if that task could be automated.

Those tricky things will not let me to understand and solve the real problem, I think that my question and my problem is clear, I will avoid "solutions" like those that are more a "patch" than a solution.

Answer 1

I am going to suggest you are not using the UserControl as intended. These are a bit like a mini-form which consumes the events of the controls on them.

Based on Handles MyUserControl.TextBox.TextChanged it appears you want the form to get involved with text changes

Typically, these allow you to create a control made of several releated controls and encapsulate the logic to perfom some task. An example would be a UserControl to define a new Employee or Product. The UserControl would consume all the events for the different steps involved and cough up a finished object at the end. A task based example would be a Search function with several controls for filters and parameters.

What they are not, are glorified Container Controls. One reason for using a UserControl form is isolate the form from those implementation details and encapsulate them for reuse.

That said, you simply have to bubble up any events you wish to expose. Using an actual UserControl, drop your TextBox onto it:

Public Class UserControl1

    Public Event MyTBTextChanged(sender As Object, e As EventArgs)

    Public Sub New()
        ' This call is required by the designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.

    End Sub

    Private Sub TextBox1_TextChanged(sender As Object, 
               e As EventArgs) Handles TextBox1.TextChanged
        RaiseEvent MyTBTextChanged(sender, e)
    End Sub
    ...

If you find that you are having to bubble up more than one or two events (or perhaps any), then you might want to rethink where the code logic is handled or whether a UserControl is the right choice (if lots of events for lots of controls are being exposed, why is there a UC at all?).