Describe the bug
This is a user feedback.

The use case involves lots regions and the user would like to select one via the region dropdown in the spectral profiler widget to check a spectral profile. The current implementation does not allow scroll down to see more regions so the use case is forbidden.

To Reproduce
Steps to reproduce the behavior:

1. load a cube
2. load a region file with lots of square regions
3. enable spectral profile
4. click the region dropdown to see the list and try scrolling to see the issue

Expected behavior
being able to scroll to see more regions for selection

Screenshots or videos

Platform info (please complete the following information):

• OS [e.g. macOS Monterey]: Sequoia
• Browser [e.g. chrome, safari, electron app]: chrome
• Browser version [e.g. 22]:
• Backend branch [e.g. dev, v3b2 release]: dev, v5, v4.1
• Frontend branch [e.g. dev, v3b2 release]: dev, v5, v4.1