Unable to Type Korean Characters in WPF TextBox When changing the ReadOnly Property

Question

We have a WPF application in which the culture is set to Korean. In the application, we have added the InkCanvas to the grid and a text box is added to the canvas. While adding the text box to the canvas, we set its ReadOnly property to true and to false when we double click on the text box. However, when we run the application and double-click the TextBox, we are unable to type Korean characters; only normal keyboard letters are typed. If we don’t set the ReadOnly property, Korean characters can be typed correctly. Could you please help us resolve this issue?"

 <Grid>
     
     <InkCanvas Name="SelectionCanvas">
         
     </InkCanvas>
 </Grid>

 TextBox textBox;
 public MainWindow()
 {
     CultureInfo koreanCulture = new CultureInfo("ko-KR");
     Thread.CurrentThread.CurrentCulture = koreanCulture;
     Thread.CurrentThread.CurrentUICulture = koreanCulture;
     InitializeComponent();
     SelectionCanvas.EditingMode = InkCanvasEditingMode.None;
     textBox = new TextBox();
    
     textBox.IsReadOnly = true;
     textBox.Width = 147;
     textBox.Height = 87;
     InkCanvas.SetLeft(textBox, 480);
     InkCanvas.SetTop(textBox, 185);
     
    
     textBox.GotFocus += TextBox_GotFocus;
     textBox.MouseDoubleClick += TextBox_MouseDoubleClick;
    
     SelectionCanvas.Children.Add(textBox);
 }
 private void TextBox_GotFocus(object sender, RoutedEventArgs e)
 {
     textBox.IsReadOnly = true;
 }
 private void TextBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
 {
     textBox.IsReadOnly = false;
     textBox.SelectAll();
 }
}

Answer 1

Hi, @Yathavakrishnan. Welcome to Microsoft Q&A.

You could solve this by forcing a refresh of the input method

    private void TextBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
    {
        textBox.IsReadOnly = false;
        textBox.SelectAll();
        //Force refresh input method
        InputMethod.SetIsInputMethodEnabled(textBox, false);
        InputMethod.SetIsInputMethodEnabled(textBox, true);
    }

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Answer 2

A text box created as ReadOnly may not have IME's initial state set to ON.

It is recommended to set PreferredImestate to be ON.

textBox = new TextBox();
textBox.IsReadOnly = true;
System.Windows.Input.InputMethod.SetPreferredImeState(textBox, System.Windows.Input.InputMethodState.On);
// or  System.Windows.Input.InputMethod.SetPreferredImeState((Window)this, System.Windows.Input.InputMethodState.On);

private void TextBox_MouseDoubleClick(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
    textBox.IsReadOnly = false;
    System.Windows.Input.InputMethod.SetPreferredImeState(textBox, System.Windows.Input.InputMethodState.DoNotCare); // keep last user ime mode
    textBox.SelectAll();
}