Feature Request: sash

[mitsuruog]

Feature request

It would be great if this toolkit provided a sash based on the VS Code sash.

Expected behavior

As the user clicks and moves the boundary of the sash, the area of the divided screen changes.
It is good to be able to pass an initial percentage of the initial split as an initial value.

For reference.

https://split.js.org/

Current behavior

The toolkit doesn't provide the component.
we need to implement it and it would be hard to adjust the theme that is provided by vscode.

Use case

This is used when users want to split the screen in WebView。

Screenshots/references