I'm interested in using a mouse-and-trackball setup: a mouse in my right hand for pointing, and a trackball in my left hand for scrolling. Is there some method available for Windows 10 that allows me to customize the meaning of input from one particular input device?

EDIT: To clarify, this is about altering Windows' interpretations of the signals from one of the mice, such that what would be cursor axis movement from one of the mice would be received as scrolling movement, while the other mouse continues to operate normally.

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    Windows can detect and use multiple keyboard or mice with no problem - have you tested this? – Leo Chapiro Jul 20 '18 at 13:35
  • Unless you mean that you want one device to be constrained to only moving the mouse and the other device is constrained to only scrolling and cannot move the mouse. If you are asking for a recommendation of software to do that then this question is off topic here. – EBGreen Jul 20 '18 at 13:38
  • I know that Windows can handle two mice. What I am asking is if there is a way to alter the interpretation of the input from one mouse so that movement is interpreted as scrolling, whereas the other one continues to behave normally. i.e., by moving one of the mice up and down, the window scrolls up and down, and left and right on that mouse scrolls left and right. If this is off-topic here, please let me know where such a question would be appropriate. It seems very much a "power user" question. – David Bruce Borenstein Jul 20 '18 at 13:49
  • Since you changed the question to not be asking for a software recommendation then it is on topic for superuser. Having said that I'm pretty sure that you would have to effectively write your own driver to do this. – EBGreen Jul 20 '18 at 14:19
  • As fas as I know the mouse and keyboard key mapping takes place in the windows registry (don't ask me where though). So you don't necessarily have to write your own driver. I have no idea if this is the case for moving the mouse, but I would think so. – Albin Jul 20 '18 at 14:58

As for the question: I think the answer is no. If you want to emulate system-wide scrolling (mouse wheel events) using the second mouse - I think it can be done only by the driver (or some driver-like software) - so if there is no such driver/software with such options for your trackball or mouse, then you're out of luck. Though it is quite plausible that such software can be written or even exists already (I don't know).

As for the general problematic of scrolling, and since you've mentioned RSI: I feel sympathetic for this problem. Yes it is quite stressing to scroll with the mouse wheel and this is needed very often - browsers, editors, etc. So this is a real problem.

Fortunately there is an excellent and free solution for this. There is an app called Autohotkey and it can emulate scrolling in a way similar to what you describe. I have made a script which emulates dynamic scrolling with mouse movements. I've been using it for 2 years and it's stable and well tested, and it's waaay better then the wheel! I just can't live without it now.

Here is github link with thorough description and how-to:

It does not answer your original question, but can solve the scrolling problem. Hope this helps.

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  • This answers the question I meant to ask, which is better. Another solution: Contour ShuttlePRO v2. The manufacturer actually thought it would not solve my problems, but it's been splendid. – David Bruce Borenstein Aug 20 '18 at 4:10

Even if I don't know a software approach (apart from writing your own driver), I'll just sum up a few options.

So - depending on your question and the comments below, I personally see two major ways (HW/SW) achieving a mouse that only works as a scroll wheel:

  • Hardware approach: a mouse usually uses sensors like hall effect sensors, optical (laser) sensors or mechanically driven once (with a spinning ball inside) for the tracking of their movement. But you only need the scroll wheel, hence it could be an idea to (irreversible) cut the sensor wires so only the scroll wheel will be connected anymore. But be aware: no input =/= no movement, as cutting the sensor off could potentially result in a floating state with unpredictable input (but this is not very likely, and if so - then pull it down with a resistor to ground

  • Software approach (preferred option 1): write your own script/driver for it which only takes use of the scroll wheel axis. https://docs.microsoft.com/en-us/windows-hardware/drivers/hid/virtual-hid-framework--vhf-

  • Build your own dedicated scroll wheel - without a mouse (preferred option 2): if you take the effort to write a script just for a scroll wheel - why don't you take an hour or so more to just build a dedicated scroll wheel, so nothing else but a scroll wheel. What you will need is a rotary encoder (better as an endless potentiometer IMHO, because they have already steppings) and program it to do the same kind of work. If you will go for the track ball, you could use a ball inside a housing with a rubber roll on the bottom that spins and drives a potentiometer or so. Look on the internet for detailed instructions, search engines are your friend.

I personally don't know any other approach, e.g. altering registry keys or device properties.

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  • Thanks! What I was really picturing was a situation where the movement of the trackball (not the scroll wheel) would result in scrolling behavior. Scroll wheels are less ergonomic than trackballs because they can only be manipulated by one finger at a time, resulting in RSI. By using the trackball itself to signal vertical and horizontal scrolling, I can use my entire left hand to pan and scroll, which seems a vastly superior setup. I actually wonder why this is not already done. – David Bruce Borenstein Jul 20 '18 at 18:40
  • @DavidBruceBorenstein because I'm now buying a whole device just to scroll... – Nelson Jul 21 '18 at 10:56
  • @Nelson, people spend hundreds on input devices to correct RSI problems they are having. A trackball can be had for less than $20. – David Bruce Borenstein Jul 21 '18 at 17:19
  • If you're getting RSI from scrolling, you need to get one of those nice mice with weighted scroll wheel that spins freely from one flick, not to buy a second pointer device just to scroll with your left hand. – Nelson Jul 21 '18 at 17:42
  • @Nelson, this was a technical question, and I do not appreciate your judging the worthiness of my technical efforts. The range in assistive technologies is as vast as the range of body shapes, sizes, and needs, and there is no one technology that addresses every kind of RSI. I think you are out of line. – David Bruce Borenstein Jul 28 '18 at 14:08

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