Review panel - Header should be fixed

Proposal

The header of the review panel should be fixed.

When the header is not fixed, it is not possible to close the panel since the "x" is out of view.

This appears to be standard behavior of the drawer component:

If the content is likely to scroll, consider placing contextual action in a fixed footer. Otherwise, contextual actions should always flow inline with the content.

Originally reported by @skahn007

You cannot click off the slide out panel to close it either, it must be scrolled back to the top and the x clicked.

Labelling as a featureenhancement since this is how content in drawer should work but it should be improved to handle long scrolling content.