Silverlight 5 + AutoCompleteBox = Bug

问题

Just installed SL5 and the toolkit, that were released few days ago.
The bug happens when you set the Text property of the AutoCompleteBox to string.Empty. It causes the AutoCompleteBox to be in a buggy state. To reproduce the bug:

add an AutoCompleteBox and a Button to the main page. Register to the TextChanged and Click events. This is the code-behind:

public partial class MainPage : UserControl
{
    public MainPage()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        auto.Text = string.Empty;
    }

    private void auto_TextChanged(object sender, RoutedEventArgs e)
    {
        // Put a break point here.
    }
} 

In runtime:

1) type "aa" into the autobox.

2) click the button.

3) type "q". ( TextChanged is still invoked).

4) erase the "q" - TextChanged is not invoked.

5) type "q" again - TextChanged is not invoked.

6) and so on, until you pick a new letter. And then it's starts over.

回答1:

I found a workaround for this strange behavior. You need a control derived from AutoCompleteBox and overrride OnApplyTemplate method to find inner TextBox of AutoCompleteBox.

When inner TextBox TextChanged event fires you need to fire TextChanged event of AutoCompleteBox control manually.

public class CustomAutoComplete : AutoCompleteBox
{
    TextBox mytext;

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        mytext = GetTemplateChild("Text") as TextBox;
        mytext.TextChanged += new System.Windows.Controls.TextChangedEventHandler(mytext_TextChanged);
    }

    void mytext_TextChanged(object sender, System.Windows.Controls.TextChangedEventArgs e)
    {
        this.Text = mytext.Text;
        OnTextChanged(new RoutedEventArgs());
    }
}

来源：https://stackoverflow.com/questions/8488968/silverlight-5-autocompletebox-bug