> For the complete documentation index, see [llms.txt](https://funcui.avaloniaui.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://funcui.avaloniaui.net/view-basics/lifetime.md).
# Lifetime
Every FuncUI view is backed by an Avalonia Control. Even when attributes of a view change, the backing control does not change. Instead, changes are mirrored to the backing Control. This is often called "patching".
Views don't hold a reference to their backing Avalonia control. The backing control is determined by the view structure.
This means if the structure changes the backing control also does change. FuncUI will ensure the new backing control is patched / has all attributes set as specified in the view.
If the view type in the structure does not match the view type in the backing structure a new backing control is created.
{% hint style="info" %}
Only backing views of the same type can be reused when the view structure changes.
{% endhint %}
## Keyed Views
Sometimes you need more control over the reuse of backing controls. This can be achieved by specifying a view key.\
\
If the view key changes a new backing view is created, no patching is attempted.
```fsharp
[
// View attributes
]
|> Button.create
|> View.withKey "button-1"
```
```fsharp
View.createWithKey "button-1" Button.create [
// View attributes
]
```
---
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