Comment 6 for bug 870693

A little of column A, a little of B. You have to understand, there is a design to all these things. There's a reason for it appearing. Even if you do not agree with it. The reason it appears is there to tell people that option is there. If Maximized, it does appear over content, but there isn't an easier way of doing it so it fades out.

In this particular case, yes, the thumb WAS immediately clickable. If you go with your proposed "fix" it would remove some usability. Think of it this way: should a button NOT be shown because it's not immediately clickable? Because I'm not in the button's area? The overlay scrollbars are designed primarily for the majority of users that find themselves with touchpads with two-finger scrolling and mouses with scroll wheels. What you propose is a step backward.

Of course, this is my opinion, but this-- and your other bug-- should be marked as invalid. However, as this is obviously a personal disagreement and I have no input into the actual development or design of overlay scrollbars, I'll leave it to you. ;)