In the resource/data pack selection menu, hovering the cursor over the scroll bar acts as if the packs that appear to its left are under it, selecting them. This is unlike the singleplayer world selection menu, the multiplayer server selection menu and the Realm selection menu.

How to reproduce:

1. Make sure you have enough resource packs so the scroll bar appears in the menu.
2. Go to the resource pack menu.
3. Hover over the scroll bar.

Expected result:

When hovering over the scroll bar, no pack would act as if it was hovered over.

Observed result:

When hovering over the scroll bar, one pack acts as if it was hovered over.