I'm on the road with my MacBook Pro (running Yosemite) and feeling very frustrated (again) that I cannot click on a slider pin in the Develop Module and then change it's value with my scroll wheel. I have two Mac laptops and both give me the same problem. It works on a Windows machine beautifully. I didn't see a fix or much discussion about this in the FAQs though there were some that 'danced' around the issue. I'm using a 5 button Logitech Bluetooth mouse with the latest Logitech software for Mac OS. I can link the mouse to Lightroom in it's setup utility. But I can't seem to figure out how to get the scroll wheel to vary the slider after I click on the sliders center pin.