DirectScrolledList bug: dec/inc buttons go into pressed state on hover

I’m making a menu class based on the DirectScrolledList and came across a weird bug.

When executing this example code and clicking the inc or dec button fast a few times the opposite button will be in a weird state: it appears as if pressed upon hovering it.

A single click on any of the buttons will reset all button behavior to normal.

This is pretty robustly reproducible by going to one end of the list and fast repeated pressing the button to go into the opposite direction a few times and then hovering over the button that was not pressed.

Any clues as to what could go wrong under the hood?