While I was learning inversion of control from autofacs example, I got idea to write my application which I will use to "feel" IoC.

So, idea was to have two buttons where one will write a message to console, and second one will write same message to text box window. Idea looked simple, but... Problem was because I wanted to follow MVVM pattern, I have created command, binded click event, then all I had to do was to change textbox text, and that was actually a problem, I couldn't find a way simply to change the value... 

Only way which I found was to send an object as parameter, something like:

CommandParameter="{Binding ElementName=IoCmessageDisplayTextBox}"

Where IoCmessageDisplayTextBox is text box on which I want to display my message.

So, here is my XAML: 

<Window x:Class="IoCtest.MainWindow"
        Title="MainWindow" Height="350" Width="525">
    <Window.DataContext><local:ClickModel />
    <Grid OverridesDefaultStyle="True">
            <ColumnDefinition Width="*" />
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="30"></RowDefinition>
        <TextBox x:Name="IoCmessageDisplayTextBox" Grid.Row="0" Grid.Column="0" TextWrapping="Wrap" Text="TextBox" AcceptsReturn="True"  HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible"/>
        <Button Grid.Row="1" Content="Write to memo" Command="{Binding MyClick}" CommandParameter="{Binding ElementName=IoCmessageDisplayTextBox}" Height="30" VerticalAlignment="Bottom"></Button>

Since I already explained how to create button click event using ICommand here, I will not do it again, I will just keep focus on method which will be executed when user clicks button. 

Method looks like this: 

public void ShowMessage(object obj)
  TextBox IoCmessageDisplayTextBox = new TextBox();
  IoCmessageDisplayTextBox = (TextBox)obj;
  IoCmessageDisplayTextBox.Text = "Hello world!";

As you can see I had to convert object which I sent as parameter to TextBox, and then I was able to change text property of my TextBox.

Example you download from here, project is prepared for IoC learning, that is why it is more dirty then usual :) I hope that results of my learning I will post soon.