How to retain the pointer cursor on a custom button in a sub-classed / restyled TextBox?

[nikolayvpavlov]

Issue

I am sub-classing the TextBox control, and want to add another button in it which always appears, similarly to AutoSuggestBox. I followed how NumberBox and AutoSuggestBox are doing it, literally replicating the styles with minor adjustments. However, the cursor on the new button changes to beam, and not to a pointer like standard buttons.

<Button x:Name="NewButton" Grid.Row="1" Grid.Column="2" Style="{StaticResource DeleteButtonStyle}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="{TemplateBinding CornerRadius}" Padding="{ThemeResource HelperButtonThemePadding}" IsTabStop="False" Visibility="Visible" AutomationProperties.AccessibilityView="Raw" FontSize="{TemplateBinding FontSize}" Width="30" VerticalAlignment="Stretch"> <FontIcon Glyph="&#xE787;" FontFamily="{ThemeResource SymbolThemeFontFamily}" FontStyle="Normal" FontSize="{ThemeResource TextBoxIconFontSize}" /> </Button>

A video illustrating the deffect:

2025-12-11_17-35-43.mp4

Weird enough, if I change the name of the change the name of my custom button to DeleteButton, the cursor works as expected and changes to a pointer!

A full reproducable example can be found here: https://github.com/mdobreva/TestCustomTextBox. The example adds the button by changing the style of the standard TextBox control, but the effect is the same.

I tried to lookup the source of TextBoxBase and TextBox, but nowhere I found how the cursor is changed / maintained. I couldn't find even how the mouse cursor is changed to beam in these controls.

What should I do to make the cursor of the new button working? And, why is the name of DeleteButton so special?

I am using Windows App Sdk 1.8 and .Net 10.

[gautambjain]

I am not sure how you have implemented that additional button. But where ever I have to change the pointer, I surround that control with the below customized Frame (implemented for Hand cursor). This I learnt from various WinUI 3 discussions.

public class HandCursorFrame : Frame
{
    protected override void OnPointerEntered(PointerRoutedEventArgs e)
    {
        base.OnPointerEntered(e);
        ProtectedCursor = InputSystemCursor.Create(InputSystemCursorShape.Hand);
    }

    protected override void OnPointerExited(PointerRoutedEventArgs e)
    {
        base.OnPointerExited(e);
        ProtectedCursor = InputSystemCursor.Create(InputSystemCursorShape.Arrow);
    }
}

[nikolayvpavlov]

You can see how I added the button in the quoted code snippet and in the reproduceable project. I am afraid your answer is not relevant to the topic.

[Skittles2519]

The SDK is probably applying custom cursor behaviors for the delete button but doesn't expose it to us, so you get the same behavior on your custom button when the name is the same.

You can make a custom textbox class and override that textbox's OnApplyTemplate and match the behavior with the Protected cursor as hinted above. Use your custom textbox control instead of the default one in your xaml to see the behavior.

CustomTextBlock.mp4

public class CustomTextBox : TextBox
{
    protected override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        if (GetTemplateChild("NewButton") is Button newBtn)
        {               
            newBtn.PointerEntered += (s, e) =>
            {
                ProtectedCursor = InputSystemCursor.Create(InputSystemCursorShape.Arrow);
                e.Handled = true; // stop parent from reacting and setting I-beam
            };

            newBtn.PointerExited += (s, e) =>
            {
                ProtectedCursor = null; // return to default behavior
                e.Handled = true;
            };
        }
    }
}

[nikolayvpavlov]

That's the thing. The SDK obviously has some hidden features, not available / visible in the source code. Ideally, there must be none such.

[castorix]

That's the thing. The SDK obviously has some hidden features, not available / visible in the source code. Ideally, there must be none such.

There is in source code :

 static_cast<CFrameworkElement*>(pTextBoxNoRef->m_tpDeleteButton.Cast<ButtonBase>()->GetHandle())->SetCursor(MouseCursorArrow);
 static_cast<CFrameworkElement*>(m_tpTextBoxQueryButtonPart.Cast<ButtonBase>()->GetHandle())->SetCursor(MouseCursorArrow);

and for TextBox :
CTextBoxView

  m_eMouseCursor = MouseCursorIBeam;
  pTextBox->SetCursor(m_eMouseCursor);

[nikolayvpavlov]

Perhaps I am looking at the wrong branch or doing something similarly silly, but I can't find the first snippets in the source. Can you please direct me to the correct source?

Anyway, this is good guidance and gives me enough info at this point.

[castorix]

Perhaps I am looking at the wrong branch or doing something similarly silly, but I can't find the first snippets in the source. Can you please direct me to the correct source?

For DeleteButton :

microsoft-ui-xaml/src/dxaml/xcp/dxaml/lib/TextBox_Partial.cpp

Line 884 in 15af68e

static_cast<CFrameworkElement*>(pTextBoxNoRef->m_tpDeleteButton.Cast<ButtonBase>()->GetHandle())->SetCursor(MouseCursorArrow);

[nikolayvpavlov]

Thanks, @castorix . I failed to find and the study the _Partial file. Equally silly, and a bit shameful of me.