Fix settings text box header not blocking input from behind

[Joehuu]

Before	After

[bdach]

This attempted fix causes another problem: after adding the input blocking container, there's a section of the settings sidebar that cannot be dragged anymore when the header isn't stickied to the top.

Current master:

https://user-images.githubusercontent.com/20418176/178329086-fae9d4d7-8a0b-416f-9f1d-6f4227ffa35d.mp4

This PR:

https://user-images.githubusercontent.com/20418176/178329113-b8887e1c-d13f-45c7-8af0-2f32bc749228.mp4

[peppy]

Going to close this one for now, as it's a very small change but has remaining issues. Feel free to open a new PR with an alternative solution if found.