My application prints (to a printer) the information shown on screen (using the Canvas control) N times. 

The process is

The user clicks a button (called Print).  

Update the Canvas with text (normally from a database but for the code below, it's hard coded)  

Print to printer  

Update the Canvas with new text (again from a database but for the code below, it's hard coded)
Print to printer

However, I can't get this to work as explained in the above process- the printer only prints the last update made. 

To make this issue replicable, I enclose the code below

My XAML

```
<Window x:Class="WpfApplication4.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <Canvas Margin="0,0,0,88" Name="canvas1">
        <TextBlock Text="Hello World" Name="TextBlock1" />
    </Canvas>
    <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="0,245,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
</Grid>
</Window>

```

and my code behind 

```
using System;
using System.Windows;
using System.Printing;
using System.Windows.Threading;
using System.Windows.Controls;

namespace WpfApplication4
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        PrintDialog dialog = new PrintDialog();
        for (int i = 1; i < 3; i++)
        {
            //showing this message box fixes the issue
            //MessageBox.Show("01");
            updateTextblock(i);

            //use the dispatcher object to ensure all renders and databinding are completed before sending to print   
            DispatcherOperation disO;
            disO = Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new Action(delegate
            {
                print(dialog);
            }
            ));   
            disO.Wait()
        }
    }

    private void print(PrintDialog dialog)
    {
        //select printer auotmatically
        PrintQueue queue = new LocalPrintServer().GetPrintQueue("Canon MG160 series WS");
        //assign the printer  
        dialog.PrintQueue = queue;

        dialog.PrintVisual(canvas1, "");
    }

    private void updateTextblock(int i)
    {
        TextBlock1.Text = "Number " + i.ToString();
    }
}
}    

```

The only thing which prints is 
Number 2

Although it has iterated and updated the canvas with Number 1 it never prints (a blank page is printed).

Any ideas what it is I need to do so each Canvas prints? Although I can get it to work by showing the messagebox it defeats the purpose of it being automated.

**EDIT**: I am now getting an error message from my printer - "Another computer is using the printer." According to other websites, I have to wait until one job finishes and then the second will start automatically but sadly, it never does.