Describe the feature that you would like added
Hi, currently Panel component overlays the whole DOM and its top height is always the top of window, this does matter when we have dynamic message bars at top. We want the panel as part of content instead of whole page, but so it's diffcult to calculate and update the latest height of panel, just like this.

My code is also the one of all components, besides message bars there are also other components at top, so can you make a type of Panel component which can be embedded to parent container?
What component or utility would this be added to
Panel
Have you discussed this feature with our team, and if so, who
No discuss yet.
Additional context/screenshots
Null.