It would be really neat if Opus would support some kind of smooth scrolling (when scrolling with a scrollwheel), similar to how web browsers do nowadays.
Sometimes when looking through a large list of files, instant jump when scrolling makes me lose the track of which file I was last looking at (if it wasn't selected).
There is Preferences / File Displays / Mouse / Smooth scrolling with mouse wheel/keyboard although it would not normally have any visible effect for the small amount of scrolling typical with a single mousewheel jump.
How many lines have you got your mousewheel configured to scroll? Does not always result in the same, predictable amount of scrolling?
It's 3 lines (which is also the default I think). I wouldn't want to reduce it because it would be too slow for majority of use cases.
Mine is 3 lines as well.
Smooth scrolling applied to such a short scroll is quite irritating in my experience, as you have to wait a second for every small scroll to happen and everything is lagging behind your mouse input.
It also doesn't seem needed for a 3 line scroll, as a small, fixed amount is easy to predict and get used to? If I move one mousewheel notch I already know where the files will move to as it's always the same, small amount. OTOH, much larger, more randomly-sized jumps can benefit from a quick animation showing the direction and distance of the jump.
I imagine a quick animation without acceleration & deceleration would be beneficial for UX and shouldn't be jarring.
Actually I've just now tried to open a PDF file in Microsoft Edge to test their smooth scrolling, and their implementation has no acceleration and has very short deceleration, it feels really good. Could you try on your end to scroll some PDF file with lines of text in Microsoft Edge, what do you think? Without acceleration, no lag would be perceived.
Smooth scrolling for tabs, that's what DOpus needs! 
I second @bytespiller's suggestion of implementing a smooth (pixelwise) scroll like Microsoft Edge does.
Especially when working with a touchpad it would be immensly helpful if the scroll would be directly related to the movement on the touchpad and not jump by a few lines after some "distance moved".
On a side note, is that actually something Directory Opus can do or is that solely related to the driver only delivering digital "mouse wheel" events and no continuous movement?
Opus gets a mouse scroll event (one per mouse wheel "notch"), and from there it's up to Opus how to present the scroll event on screen. Currently it scrolls (or rather, shifts instantaneously) by amount defined in Windows mouse settings (e.g., 3 lines).
EDIT: I missed somehow that your side note touches upon (no pun intended) the laptop touchpad scrolling, I have no idea about that.
As some of you..
I'm not a fan of smooth scrolling if scrolling gets laggy or mushy and does not reflect actual movement of mouse or number of button clicks anymore. Even on modern PCs it's eating up performance and things get rather slow and unprecise with this "invention"..
BUT, there is a need for smoother scrolling for me too! o)
It does not need to be on a pixel level here though..
If you are using the Tiles viewmode or the Details+Thumbnails viewmode, each line is much higher in the file display, maybe 50, 200 or even more pixel and once you touch your mouse wheel, things scroll by very fast and you totally lose track of what you are viewing.
I'm also not a fan of animated scrolling (or is that the actual smooth scrolling we are talking about?), but for the Tiles / Details+Thumbnails mode some "in between" frames would be good. These modes should scroll like the regular Thumbnails mode. This one does not scroll by full thumbnail height (unless you use keyboard!) and that's kinda nice to use that way, I actually always wondered why the other viewmodes do not work like this mode does.
I think a good point was raised about touchpads, where you actually swipe in a smooth motion. It would indeed make sense for the scrolling to reflect this motion as accurately as possible. Same as on a smartphone.
The scrollwheel on my mouse on the other hand (well, actually i use the same hand 
), you can feel the increments or click-stops or whaddayacallthem. They're like this on purpose, so it makes sense for the scrolling to have these steps as well.
But if i were to have a touch mouse ..
And how about the Microsoft Surface, or other convertibles with full-on touchscreens?
I haven't used Opus on any laptop yet though so can't judge how it is now.
I've connected with RDP to my Win10 machine (using the free Microsoft Remote Desktop app on my iPad), and smooth scrolling in Opus already works, you can flick the lister contents with your finger and it will scroll per-pixel as smoothly as if you were dragging the scrollbar, or using any native touch-based app. But I think that functionality is courtesy of Windows itself behind-the-scenes, and not something Opus explicitly does.
Ah good, that's what i'd expect.
Maybe then that makes it easier to activate the same for mouse.
But then why wouldn't a touchpad work the same?
At least that's what DrBones implied. Probably a driver/compatibility thing then indeed.
@bytespiller good to know. That is what I had hoped for but I unfortunately have only this one laptop with an Alps Touchpad which for some reason doesn't scroll smoothly.
It is probably a driver issue as @MMXVII mentioned and not a DOpus one. I will try to find a "better" laptop and try again, thanks.
I still do like smooth scrolling but not at the expense of lag free input but my main issue lies elsewhere apparently.
Having a Samsung, Lenovo and Microsoft tablet, all Win 10 Pro, all smooth scrolling in DO when using touch.
I've just noticed how smooth scrolling works in the Windows 10 Start Menu's list of installed programs (when using the scrollwheel). That kind of smooth scrolling isn't bothersome no matter how little the user scrolls (besides, a speed option could be present too).
The current Preferences / File Displays / Mouse / Smooth scrolling with mouse wheel/keyboard really doesn't do anything noticeable.
It's not just eye candy, this would enable users to scroll faster than usual (not to mention more comfortable) due to easier visual tracking enabled by the smooth scrolling feature.
Firefox lets you adjust smooth scrolling behavior however you want with multiple flags. I've made it more or less identical to the way Windows 10's Start Menu has it.
I think the way Mozilla did it is the way to go, because users have different trackpads / mice and different drivers and settings on those trackpads / mice, so you can't really have a one-size-fits-all solution.
Yeah I'd really like smooth scrolling like in the Firefox or the Start Menu, I hope Opus 13 in the future will have that.
Like I've said 3 years ago, it would enable people to scroll faster.
If you scroll fast now in DO12, the screen turns into a jumbled mess of randomly switching pixels (visual tracking is very difficult with this old-school instant-jumps implementation of scrolling).
It's not (just) eye candy, it really aids productivity and UX comfort.
So please @jon @leo , your eyes aren't getting any younger either, so wouldn't it be nice for you personally too to have this? 