Before 1.13, I had no issue scrolling in my hotbar. What I am used to is 1 notch moved on my mouse wheel equals 1 slot moved. But in the 1.13 Update, the amount I need to scroll to move 1 slot is almost random. Sometimes it takes 5 notches, sometimes 10. It is very inconsistent. Here are the possible solutions to this:
Add a mouse wheel sensitivity slider to the control options.
Make the mouse wheel scrolling more consistent.
Add a hotkey control option to cycle hotbar slots instead.
Just set the scroll wheel sensitivity to it's original value.
Please fix this. Doing PVP on a server is now very tough since I can't cycle hotbar slots easily.
I know you didn't intend for this to happen, so I'm considering this a bug.
Please comment if you are using a gaming mouse and have this problem too.
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See workaround in MC-123773