This is a minor issue, but maybe it's enough to mention depending on your navigation habits.
I have my Windows mouse wheel settings configured to advance the screen 3 lines at a time while using the scroll wheel. This works just fine in the Notes tab. But in the Bible tab (KJV 1900 and YLT), each turn segment of the wheel advances almost the entire page at a time, so that scrolling is rather jumpy. I have the columns set to "None" -- and using the up/down arrows on the keyboard advance 3 lines per press as desired.
Yes, I can just use the arrow keys instead of the mouse wheel (which is why it's a minor issue), but thought it would still be worth mentioning as I tend to use the scroll wheel while advancing through the text, and maybe others do as well. It's especially an issue because these days I need to have my monitor display enlarged, so when I have the inline interlinear numbers activated, I might only see part of a verse in the Bible tab (if the verse is fairly long, or if the previous verse takes up the top half of the Bible tab with the current verse is displayed in the bottom half). So that breaks up the verses quite a bit, having to scroll up and down repeatedly in order to digest the whole verse. If I could incrementally scroll in the Bible tab as I can in the Notes tab (or as with the arrow keys), it would certainly make reading much easier from a usability standpoint.
The only reason I bother to mention such a small issue is that I assume since it's possible to incrementally scroll with the arrow keys, it should be possible with the scroll wheel as well -- but admittedly I'm not a Windows developer and don't really know. Maybe there's just a tweak/setting to adjust. I have also tried using more than one mouse.
Since I've posted a few "issues," I'll also post something on the positive side that the UI is really nice. 
Thank you!