Improve responsiveness and differentiation of the scroll bar in the left panel
The scroll bar indicating where you are in the leftmost panel containing the list of accounts and folders is black on black--so black that it took me a while to discover it and on one of my computers it is pretty much invisible. This is taking minimalism too far. For a while I was guessing at where I was and clicking on the area on the scroll bar was supposed to be. I'm not sure what acton is supposed to invoke the scrolling feature, but it seems to be absent a lot of the time when I want it, and instead I end up clicking on a folder that I don't want to select. Please make it both persistent and visible.

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Patrik commented
The scroll bar still (v. 2.6.1) needs improvement; at least with a Wacom tablet the scroll bar does not appear at all when hovering over the panel, forcing me to use my laptop's trackpad when wanting to navigate to a folder.