Clicking on the "X" button added by TextBoxHelper.ClearTextButton does not clear the databinding target

What steps will reproduce this issue?

1. Click on Textbox1
2. Enter some string, eg “123”
3. Press TAB or click on other textboxes
4. The string, “123” will be shown in Textbox2 (due to data binding)
5. Click the “X” button on Textbox1
6. The string on Textbox2 is not cleared

I noted that for the “X” button to clear the databinding target,

1. The textbox where the “X” is going to be clicked on must be the active control (focused) or
2. After clicking the “X” button, focus the textbox which the “X” button was clicked on by clicking on it, and then click on other control to make to lose focus.

Expected outcome

Upon clicking the “X” button, the databinding target should be cleared immediately.

Code

cs

using System.Windows;

namespace Test
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {


        public string MyString
        {
            get { return (string)GetValue(MyStringProperty); }
            set { SetValue(MyStringProperty, value); }
        }

        // Using a DependencyProperty as the backing store for MyString.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty MyStringProperty =
            DependencyProperty.Register("MyString", typeof(string), typeof(Window1), new PropertyMetadata());



        public Window1()
        {
            InitializeComponent();
        }
    }
}

XAML

<Window x:Class="Test.Window1"
        x:Name="this"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Test"
        xmlns:mahapps="http://metro.mahapps.com/winfx/xaml/controls"
        mc:Ignorable="d"
        Title="Window1" Height="300" Width="300">
    <StackPanel DataContext="{Binding ElementName=this}">
        <Label Content="Textbox1" />
        <TextBox Text="{Binding MyString}" mahapps:TextBoxHelper.ClearTextButton="True" />

        <Label Content="Textbox2" />
        <TextBox Text="{Binding MyString}" mahapps:TextBoxHelper.ClearTextButton="True" />

        <Label Content="Textbox3" />
        <TextBox />
    </StackPanel>
</Window>

Environment

• MahApps.Metro 1.6.0-alpha013 (nuget)
• Windows OS 10
• Visual Studio 2017
• .NET Framework 4.6.2

[thoemmi]

Looking at PR #3046, I think it makes sense. 👍

[punker76]

@programatix This is by WPF, cause the default of UpdateSourceTrigger for Text() is LostFocus, so if you change this to UpdateSourceTrigger=PropertyChanged all should work as expected.

<Label Content="Textbox1" />
<TextBox Controls:TextBoxHelper.ClearTextButton="True" Text="{Binding MyString, UpdateSourceTrigger=PropertyChanged}" />
<Label Content="Textbox2" />
<TextBox Controls:TextBoxHelper.ClearTextButton="True" Text="{Binding MyString, UpdateSourceTrigger=PropertyChanged}" />

One of the UpdateSourceTrigger values. The default is Default, which returns the default UpdateSourceTrigger value of the target dependency property. However, the default value for most dependency properties is PropertyChanged, while the Text property has a default value of LostFocus.

https://msdn.microsoft.com/en-us/library/system.windows.data.binding.updatesourcetrigger(v=vs.110).aspx