Basically, the bug is as the title says. When the grid has a scrollbar, it covers the little action dot in the bottom right corner of a cell when you're in Firefox. Here's an example of what I'm talking about, taken straight from the first example on the website
Even worse, if you try to use that action corner, the scrollbar covers it. So, it is impossible to click and drag on that action corner
In contrast, here's how it looks in Chrome, which I believe is the intended behavior. The scroll is to the right of the action button, allowing a user to use it

Basically, the bug is as the title says. When the grid has a scrollbar, it covers the little action dot in the bottom right corner of a cell when you're in Firefox. Here's an example of what I'm talking about, taken straight from the first example on the website
Even worse, if you try to use that action corner, the scrollbar covers it. So, it is impossible to click and drag on that action corner
In contrast, here's how it looks in Chrome, which I believe is the intended behavior. The scroll is to the right of the action button, allowing a user to use it