public event InteractiveActionExecutingEventHandler InteractiveActionExecuting

Public Event InteractiveActionExecuting As InteractiveActionExecutingEventHandler

// Handles the InteractiveActionExecuting event
void ReportViewer1_CustomInteractiveActionExecuting(object sender, InteractiveActionCancelEventArgs args)
{
    var strB = new System.Text.StringBuilder();
    strB.AppendLine("ReportItem name: " + args.Action.ReportItemName);

    if (args.Action.Type == Telerik.Reporting.Service.ActionType.CustomAction)
    {
        foreach (var p in args.Action.Parameters)
        {
            strB.AppendLine(string.Format("Parameter \"{0}\" value: {1}", p.Key, p.Value));
        }
    }

    strB.AppendLine(string.Format("Mouse cursor position: {0}; Item bounds: {1}", args.CursorPos, args.Bounds));

    System.Diagnostics.Debug.WriteLine(strB.ToString());
}

' Handles the InteractiveActionExecuting event
Private Sub ReportViewer1_CustomInteractiveActionExecuting(sender As Object, args As InteractiveActionCancelEventArgs) Handles ReportViewer1.InteractiveActionExecuting

    Dim strB = New System.Text.StringBuilder()
    strB.AppendLine("ReportItem name: " + args.Action.ReportItemName)

    If args.Action.Type = Service.ActionType.CustomAction Then
        For Each p As KeyValuePair(Of String, Object) In args.Action.Parameters
            strB.AppendLine(String.Format("Parameter ""{0}"" value: {1}", p.Key, p.Value))
        Next
    End If

    strB.AppendLine(String.Format("Mouse cursor position: {0}; Item bounds: {1}", args.CursorPos, args.Bounds))

    MessageBox.Show(strB.ToString())
End Sub

// Handles the InteractiveActionExecuting event
void ReportViewer1_CancelingInteractiveActionExecuting(object sender, InteractiveActionCancelEventArgs args)
{
    if (args.Action.Type == Telerik.Reporting.Service.ActionType.UrlNavigation)
    {
        if (!args.Action.Url.StartsWith("https"))
        {
            args.Cancel = MessageBox.Show("You are about to navigate to a non-secure page. Continue?", "Warning", MessageBoxButton.OKCancel) != MessageBoxResult.OK;
        }
    }
}

' Handles the InteractiveActionExecuting event
Private Sub ReportViewer1_CancelingInteractiveActionExecuting(sender As Object, args As InteractiveActionCancelEventArgs) Handles ReportViewer1.InteractiveActionExecuting

    If args.Action.Type = Telerik.Reporting.Service.ActionType.UrlNavigation Then
        If Not args.Action.Url.StartsWith("https") Then
            args.Cancel = MessageBox.Show("You are about to navigate to a non-secure page. Continue?", "Warning", MessageBoxButton.OKCancel) <> MessageBoxResult.OK
        End If
    End If
End Sub