In versions up through 1.12.2, tilting my scroll wheel left and right would count as buttons 6 and 7 under the options for controls. I would make heavy use of this to switch to slots 2 and 8 in my hotbar.
Since version 1.13, tilting the scroll wheel on my mouse no longer registers as an input in the Minecraft controls setting. Nothing happens. I am still able to map buttons 1-5, but not 6 and 7.