Inheritance/user control problem

I have the following event in a VB2005 User Control:

Public Event ButtonClicked(ByVal Sender As Object, ByVal E As System.EventArgs)

This code in the User Control is the only code that calls the event:

Private Sub HandleButtons(ByVal Sender As Object, ByVal E As System.EventArgs) Handles btnFirst.Click, btnLast.Click, btnNext.Click, btnPrev.Click

Dim BTN As Button = DirectCast(Sender, Button)

Select Case BTN.Name

Case "btnFirst"

CurrentRecord = 1

Case "btnLast"

CurrentRecord = RecordCount

Case "btnNext"

CurrentRecord += 1

Case "btnPrev"

CurrentRecord -= 1

End Select

RaiseEvent ButtonClicked(Sender, E)

End Sub

I added the User control to a form (FORM1) and add the following code:

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

With NavControl1

.RecordCount = 10

.CurrentRecord = 1

End With

End Sub

Private Sub HandleButtons(ByVal Sender As Object, ByVal E As EventArgs) Handles NavControl1.ButtonClicked

Dim CTRL As Control = DirectCast(Sender, Control)

Dim strBTN As String = String.Empty

Select Case CTRL.Name

Case "btnFirst"

strBTN = "FIRST"

Case "btnLast"

strBTN = "LAST"

Case "btnNext"

strBTN = "NEXT"

Case "btnPrev"

strBTN = "PREVIOUS"

End Select

MessageBox.Show(String.Format("The {0} button was clicked", strBTN))

End Sub

FORM1 runs without any problems. If I remove the code from FORM1 and inherit a new form (FORM2) from FORM1 and add the same code to FORM2 I get an error “Button Click event is read only and can not be changed” when I attempt to open FORM2 in the designer.

Can anyone see what’s causing the problem What can I do to correct it

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Inheritance/user control problem

Shailendra18
Nope.
Bassel Samir Banbouk
try using the overridable attribute especially if you are going to want to change the code in the inherited form:

Private Overridable Sub HandleButtons....
bhoffmancsi
You're on to something. I tried to reproduce what you did and got major problems. At one point, I got both Form1 and Form2 unable to display their designers with "Catastrophic failure" error messages (0x8000FFFF).

I have to admit that I don't know enough about event inheritance to really give a good answer. Seeing an error message from trying to implement the ButtonClicked event handler in Form2 kinda made sense: you can only inherit the events the the base form raises.

So I tried to rework it by having the UserControl raise an event in Form1:

Public Class Form1
Public Event ButtonClicked2(ByVal Sender As Object, ByVal E As System.EventArgs)

Private Sub UserControl11_ButtonClicked(ByVal Sender As Object, ByVal E As System.EventArgs) Handles UserControl11.ButtonClicked
RaiseEvent ButtonClicked2(Sender, E)
End Sub
End Class

Public Class Form2
Inherits Form1

Private Sub Form2_ButtonClicked(ByVal Sender As Object, ByVal E As System.EventArgs) Handles MyBase.ButtonClicked2
Debug.Print("Click")
End Sub
End Class

No "Click"....
donall
I don't want to change or overwrite any of the code in the User Control and FORM1 has no code. Changing the sub in FORM2 from "ButtonClicked" to "ButtonTest" did not help.
Dan.B

Make sure that the accessibility for NavControl1 is Public, Friend, or Protected.

Hope that helps,
Mario Lucin
Try changing the way you declare the event. Since this is a standard format event handler, declare it as such:

Instead of:
Public Event ButtonClicked(ByVal Sender As Object, ByVal E As System.EventArgs)

Try:
Public Event ButtonClicked As EventHandler

HTH
Inheritance/user control problem

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