click event is fired twice on an enhanced Button Control

[Roberto Kohler]

I created an enhanced Button Control in ASP NET 2.0 to add a delete
confirmation message and to disable the button if the user does not have
access.
The new button control has a "ConfirmMessage " property where you can set the
message you want displayed and a "SecurityKe y" property to set the security
key for the button.
The securitykey works fine. The button is disabled if the user should not
have access to it.
The problem I have is with delete confirmation message. When the user
accepts the confirm message, the click event is fired twice.

If I look at the html source on the client, the button has 2 onclick
statements:
onclick="javasc ript:return confirm('Do you wish to delete this record ?');"
onclick="javasc ript:WebForm_Do PostBackWithOpt ions(new
WebForm_PostBac kOptions(..."

I override the AddAttributesTo Render with the attached code.

If I take out the writer.AddAttri bute(HtmlTextWr iterAttribute.O nclick,
onClickScript) statement, then clicking on the button does nothing

Any help would be appreciated.

Protected Overloads Overrides Sub AddAttributesTo Render(ByVal writer As
HtmlTextWriter)

writer.AddAttri bute(HtmlTextWr iterAttribute.H ref, "#")

Dim onClickScript As String = "javascript :"
Dim actionScript As String = String.Empty

' Do not validate in design mode
If Not Me.DesignMode Then
If Not authorizedAcces s(Me.SecurityKe y.ToString, "E", "B")
Then
Me.Enabled = False
Else
If Me.ShowConfirm Then
actionScript = String.Concat(" return confirm('",
EscapeJavaScrip t(ConfirmMessag e), "');")
End If
End If
End If

If actionScript = String.Empty Then
actionScript =
Me.Page.ClientS cript.GetPostBa ckEventReferenc e(Me, "")
End If

If Me.Enabled AndAlso (Not (Me.Page Is Nothing)) Then
onClickScript += String.Concat(c onfirmScript, actionScript)
writer.AddAttri bute(HtmlTextWr iterAttribute.O nclick,
onClickScript)
End If

If ShowStatusBarTe xt Then
writer.AddAttri bute("onmouseov er",
String.Concat(" javascript:wind ow.status='", EscapeJavaScrip t(StatusBarText ),
"';return true;"))
writer.AddAttri bute("onmouseou t",
"javascript:win dow.status='';r eturn true;")
End If

MyBase.AddAttri butesToRender(w riter)

End Sub

Protected Overridable Function GetClientValida tedPostback(ByV al
control As Control, ByVal confirmScript As String) As String
Dim text1 As String =
control.Page.Cl ientScript.GetP ostBackEventRef erence(control, confirmScript)
Return ("{if (typeof(Page_Cl ientValidate) != 'function' ||
Page_ClientVali date()) " + confirmScript + text1 + "} ")
End Function