> For the complete documentation index, see [llms.txt](https://docs.radicalframework.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.radicalframework.com/release-1/behaviors/textbox-behaviors/textbox-disable-undo-manager.md).

# DisableUndoManager

The WPF `TextBox` that shipped with the .net 3.5 release had a bug, fixed in later versions, that prevents to set the `UndoLimit` property to 0, Radical provides a behavior as a workaround:

```markup
<TextBox Text="bla bla...">
    <i:Interaction.Behaviors>
        <behaviors:DisableUndoManagerBehavior />
    </i:Interaction.Behaviors>
</TextBox>
```

the behavior is defined in the `http://schemas.topics.it/wpf/radical/windows/behaviors` xml namespace.