/// <summary>
/// Handles the IsVisibleChanged event of the MainPage control.
///
/// this should be done as a property trigger or behaviour and not done in 'code behind'...
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
private void MainPage_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
{
if (!_initialised)
{
_initialised = true;
_model.Clear();
}
}