>I'm writing a WPF application using VS 2008 for a client that wants to force the users to scan a barcode for data entry into MOST textboxes. But they want a password protected override button on the form that will allow a person to manually enter the text if, for some reason, the barcode is unreadable or the reader is not working.
>
>Does anybody know of a way to ignore data entry into textboxes using the keyboard, but allow barcode scanned text?

On the timing approach maybe something like this:

<Window x:Class="WpfApplication2.Window2"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window2" Height="300" Width="300">
    <DockPanel>
        <TextBox DockPanel.Dock="Top" x:Name="TB" KeyDown="TextBox_KeyDown"></TextBox>
        <TextBox DockPanel.Dock="Top" x:Name="RealBox" IsEnabled="False"></TextBox>
    </DockPanel>
</Window>

Behind:

using System;
using System.Windows;
using System.Windows.Input;

namespace WpfApplication2
{
    public partial class Window2 : Window
    {
        public Window2() {InitializeComponent(); }

        private DateTime start;
        bool counting;

        private void TextBox_KeyDown(object sender, KeyEventArgs e)
        {
            if (counting)
            {
                if (e.Key == Key.OemPlus)
                {
                    //End input
                    if (DateTime.Now < start.AddSeconds(2) && TB.Text.Length==6)
                    {
                        RealBox.Text = TB.Text + "+";
                    }
                    else
                        RealBox.Text = string.Empty;
                    counting = false;
                    TB.Text = string.Empty;
                    e.Handled = true;
                    return;
                }
            }
            if (!counting && e.Key == Key.OemPlus)
            {
                start = DateTime.Now;
                counting = true;
            }
        }
    }
}

Only input with a length of 6 characters and starting and ending with a + sign that is entered in less than 2 seconds will get into the 'RealBox'. Obviously you will need to reduce the time check in real life.