[Bug]: HeaderPanel does not allow vertical scrolling when expanded

[metonym]

Package

@carbon/react

Browser

Chrome

Package version

1.63.2

React version

18.x

Description

When expanded, the HeaderPanel does not allow vertical scrolling on the content. The expected behavior is that a vertical scrollbar should appear as needed.

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Reproduction/example

https://react.carbondesignsystem.com/?path=/story/components-ui-shell-header--header-w-actions-and-switcher

Steps to reproduce

1. Visit https://react.carbondesignsystem.com/?path=/story/components-ui-shell-header--header-w-actions-and-switcher
2. Open the switcher.
3. Resize your browser viewport so that the height is smaller than the content
4. Note how you cannot vertically scroll the content

Suggested Severity

Severity 3 = User can complete task, and/or has a workaround within the user experience of a given component.

Application/PAL

No response

Code of Conduct

• I agree to follow this project's Code of Conduct
• I checked the current issues for duplicate problems