In Firefox 58.0.2 on Ubuntu, scrolling goes fine when you are on the middle of the scrollbar. When I want to scroll, I quickly move my mouse completely to the right side of the screen and don’t look at where exactly the point of the mouse is before I press to scroll. What happens is that instead of scrolling, you have selected a message and preview window opens but no scrolling through messages takes place.
What I mean is that the ability to scroll is sensitive to where your mouse pointer is. If you move the pointer completely to the right of the scrollbar / screen, then the focus of the pointer is not on the scrollbar any more but is highlighting the underlying message. Visually the pointer looks to be still on the scrollbar but effectively not.
So, if you now press the button because you want to select the scrollbar to scroll down, it is not selecting the scrollbar but the highlighted message underneath the scrollbar. And because you are clicking a message, it shows the preview pane.
Could be a hick-up of Firefox on Ubuntu but this is at least what I am experiencing.
Look, that you personally don’t find it a problem is your opinion. I have a different one. After only playing with R7 for an hour, I found it already annoying enough to post it here. With my folders with larger email numbers I use it all the time and get irritated all the time by it there it is impossible to scroll without looking first where the mouse pointer exactly is. So please make at least an issue of it? This shouldn’t be hard to fix.
No, I didn’t do that. But what what does it matter anyway? If you press wheel or left mouse button, the underlying message is selected. I don’t get your point here.