Question

I want to create a textbox which text binds an integer (e.g 123456789), but it shows the thousand separator (eg 123.456.789), but when I select the textbox for editing it the string returns without separator, until the textbox loses the focus, just like in Excel. Any advice?

Answer 1

Use a Trigger which formats the value if the TextBox isn’t selected

<Style TargetType="{x:Type TextBox}">
    <Setter Property="Text" Value="{Binding SomeValue, StringFormat=N2}" />
    <Style.Triggers>
        <Trigger Property="IsKeyboardFocusWithin" Value="True">
            <Setter Property="Text" Value="{Binding SomeValue}" />
        </Trigger>
    </Style.Triggers>
</Style>

You can also use a Converter for formatting if you can’t easily format with StringFormat