Creating a custom input dialog

In the last couple of articles, we've looked at using the built-in dialogs of WPF, but creating your own is almost just as easy. In fact, you really just need to create a Window, place the required controls in it and then show it.
However, there are a few things that you should remember when creating dialogs, to ensure that your application acts like other Windows applications. In this article, we'll create a very simple dialog to ask the user a question and then return the answer, while discussing the various good practices that you should follow.

Designing the dialog

For this particular dialog, I just wanted a Label telling the user which information we need from him/her, a TextBox for entering the answer, and then the usual Ok and Cancel buttons. I decided to add an icon to the dialog as well, for good looks. Here's the end result: 

And here's the code for the dialog:

<Window x:Class="WpfTutorialSamples.Dialogs.InputDialogSample"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Input" SizeToContent="WidthAndHeight" WindowStartupLocation="CenterScreen"
        ContentRendered="Window_ContentRendered">
    <Grid Margin="15">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <Image Source="/WpfTutorialSamples;component/Images/question32.png" Width="32" Height="32" Grid.RowSpan="2" Margin="20,0" />

        <Label Name="lblQuestion" Grid.Column="1">Question:</Label>
        <TextBox Name="txtAnswer" Grid.Column="1" Grid.Row="1" MinWidth="250">Answer</TextBox>

        <WrapPanel Grid.Row="2" Grid.ColumnSpan="2" HorizontalAlignment="Right" Margin="0,15,0,0">
            <Button IsDefault="True" Name="btnDialogOk" Click="btnDialogOk_Click" MinWidth="60" Margin="0,0,10,0">_Ok</Button>
            <Button IsCancel="True" MinWidth="60">_Cancel</Button>
        </WrapPanel>
    </Grid>
</Window>

using System;
using System.Windows;
namespace WpfTutorialSamples.Dialogs
{
        public partial class InputDialogSample : Window
        {
                public InputDialogSample(string question, string defaultAnswer = "")
                {
                        InitializeComponent();
                        lblQuestion.Content = question;
                        txtAnswer.Text = defaultAnswer;
                }

                private void btnDialogOk_Click(object sender, RoutedEventArgs e)
                {
                        this.DialogResult = true;
                }

                private void Window_ContentRendered(object sender, EventArgs e)
                {
                        txtAnswer.SelectAll();
                        txtAnswer.Focus();
                }

                public string Answer
                {
                        get { return txtAnswer.Text; }
                }
        }
}

The code is pretty simple, but here are the things that you should pay special attention to: