Provides an opaque background for [Control] children.
Panel is a [Control] that displays an opaque background. It's commonly used as a parent and container for other types of [Control] nodes.
https://godotengine.org/asset-library/asset/520
https://godotengine.org/asset-library/asset/516
https://godotengine.org/asset-library/asset/523
The style of this [Panel].