Expander header + TextBox

[JanVanharaBP]

Describe the bug

I have expander and in header I have TextBox. When user writes into the textbox the expander on each space expands/hides content. Expander's template is button template and it reacts on space as Accelerator key - similarly as button does - and space is basically use the button command.

Why is this important?

I may be doing something wrong, but I tried few ways to work it out without luck. Its not nice to expande/hide expander's content on each space.

Steps to reproduce the bug

<Expander HorizontalAlignment="Stretch"
          HorizontalContentAlignment="Stretch"
          IsExpanded="{x:Bind ViewModel.Expanded, Mode=TwoWay}">
    <Expander.Header>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="Auto"/>
            </Grid.ColumnDefinitions>
            <TextBlock Grid.Column="0"
                       Text="Name: "
                       VerticalAlignment="Center"/>
            <TextBox Grid.Column="1" 
                     Text="{x:Bind ViewModel.Name, Mode=TwoWay}"
                     Margin="10,0,10,0"/>
            <CheckBox Grid.Column="2"
                      Content="Enabled"
                      Padding="8,8,0,0"
                      IsChecked="{x:Bind ViewModel.IsEnabled, Mode=TwoWay}"/>
            <Button Grid.Column="3"
                    Command="{x:Bind ViewModel.OpenPermissionsCommand, Mode=OneWay}"
                    Margin="0,0,5,0">
                <StackPanel Orientation="Horizontal">
                    <FontIcon Glyph="&#xE83D;"/>
                    <TextBlock Text=" Permissions"/>
                </StackPanel>
            </Button>
            <Button Grid.Column="4"
                    Style="{ThemeResource AccentButtonStyle}"
                    Background="{ThemeResource SystemFillColorCriticalBrush}"
                    Content="Delete" Margin="5,0,0,0"
                    Command="{x:Bind ViewModel.DeleteCommand, Mode=OneWay}"/>
        </Grid>
    </Expander.Header>
 <!-- Some content here -->
</Expander>

Now when you write in such expander, then it expands on space.

Actual behavior

No response

Expected behavior

When focus is on TextBox, underlying Expander header doesn't process it.

Screenshots

No response

NuGet package version

2.0.1

Windows version

Windows 10 (21H2): Build 19044

Additional context

No response

[w-ahmad]

This behavior appears to be by design rather than a bug. The Expander control handles the Space key internally to toggle its expanded state.

If you need to suppress this behavior, you can handle the key event before it reaches the Expander. One approach is to handle the KeyDown event on the root element within the Expander.Header and mark the event as handled.

<Expander.Header>
    <Grid KeyDown="Grid_KeyDown">
        <Grid.ColumnDefinitions>
        .................

private void Grid_KeyDown(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs e)
{
    e.Handled = true;
}

[TekuSP]

This is clearly a bug. This should be accelerator key, which you should be able to re-bind to different key, or disable completely.

[TekuSP]

Duplicate of: #4407