Simple as that: On OSX Mavericks, touchpad scrolling doesn’t work with the Logitech T651 Trackpad in MonoDevelop-Unity 4.0.1. Scrolling works fine with the Apple Magic Touchpad, and the Logitech works fine everywhere else (specifically including inside Unity proper), but Logitech + MonoDevelop = death. May not be related to Mavericks, but that’s what I’ve got; is definitely related to the new MonoDevelop, since this problem never happened with Unity <= 4.2.2.
I have the same problem with my Apple Mighty Mouse. It seems to be a bug with MonoDevelop version 4.0.1.
Same here, just upgraded to Mavericks and new Unity 4.3 with MonoDevelop 4.0.1
I have a Logitech Anywhere MX mouse though.
I love Unity, but I gotta say MonoDevelop is one of the weirdest pieces of software I’ve ever seen. Some of its bugs, I don’t even know how to create deliberately. How is it receiving scroll messages that lets it tell the difference between a Magic Touchpad and a Magic Mouse, so that it can choose to ignore one but not the other? Sigh. 
same here - logitech performance mx mouse and mavericks
Have you guys submitted a bug on it?
Good point WarHead. I’ve just submitted a ticket via the ‘Report a Bug’ feature in Unity. If I get a issue tracker ticket I’ll link it here so you guys can vote it up.
Issue 567130 from October 2nd :-x covers this. Vote early, vote often!
I know the bug has already been reported, but I thought I would add my experience. The scrolling issue applies to me as well with the following specs:
OSX Mavericks
Unity 4.3.1
MonoDevelop 4.0.1
Logitech Performance MX Mouse
However, I also have the Logitech T650 (not T651) touchpad, and the scrolling DOES work in MonoDevelop 4.0.1 for some reason for that touchpad specifically. My Logitech Performance MX Mouse DOES NOT work for scrolling though.
I tried posting this before, so hopefully it won’t double-post, but I found a fix.
I’m using a Performance MX with MonoDevelop 4.0.1 mouse as well. To fix it, I went into [System Prefernces] - > [Logitech Control Center] and set the scroll wheel to “Nothing”, then back to “Vertical Scroll”. After that, scrolling worked.
Upon further testing, I seems that caused my scroll settings to be reset to default, and if they are set too low, MonoDevelop won’t recognize anything. So I guess the real problem was that the settings for the scroll wheel were somehow too minuscule to be picked by MonoDevelop or something like that.
Well I’ll be.
I tried that solution (resetting the scroll wheel in the Logitech Control Center) and now scrolling with my Logitech Performance MX mouse is working again in MonoDevelop 4.0.1!
Thanks for your help MatValadez!
MatValadez tip worked for me as well, but not before I also turned down the mouse wheel acceleration for my MX Revolution mouse
i have a mighty mouse… is there any solution for it? 
Same here with Logitech MX 1000 !
Unfortunately, MatValadez fix didn’t work for me
Well the bug is still here. I understand it takes time to put in the fix, but this problem was fixed by Xamarin ONE YEAR AGO.
Any news on this ?
The workaround mentioned earlier still works to ‘fix’ the problem. However, I have to say having my sensitivity so high really is annoying to the rest of the programs on my computer.
The workaround works only once for me, after that it stops working for some reason. It doesn’t “fix” the problem for me.
The fact remains that its already been one year since the fix is out… Hoping they will solve this issue sooner rather than later….
this is still not working for me. Has anyone found a solution ? any Unity devs know if there is a fix for this soon ?
@KenConrad , scrolling is now working for me in MonoDevelop 4.0.1 with my Logitech T651 trackpad. HOWEVER, it no longer scrolls with my Logitech Performance MX mouse. I’m not sure why both of them can’t seem to work at the same time. I’m running OSX 10.9.4, in case that helps.
yeah i can use my apple track pad, but it is frustrating to have to switch back and forth… my MX mouse will not work no matter what i have tried. I would much rather use the mouse other the trackpad.
if you are not using your trackpad will your mouse work ?
I am on 10.9.2, and i would rather not have to update because of other software, but i will make a partition if i need to…