Capture mouse clicks on WPF TextBox

I want to capture mouse clicks on a TextBox:

<Window x:Class="WpfApplication2.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window1" Height="300" Width="300">
    <Grid>
        <TextBox x:Name="t" MouseDown="TextBox_MouseDown"
                 MouseLeftButtonDown="TextBox_MouseLeftButtonDown"
                 MouseLeftButtonUp="TextBox_MouseLeftButtonUp"
                 Height="50" />
    </Grid>
</Window>

Now I only receive a mouse click event when the user first enters the TextBox. After this TextBox has keyboard focus, I do not receive mouse click event anymore. Any idea how to get this working?