I recently switch companies and am still working out setting up my profile. I am using SW 2016, SP 4.0 (previous company was SP 3.0).
One thing that I am noticing that I didn't at my previous company, is that when I select a component in the graphics view (usually just a face of the component), and then hover over the design tree and use my mouse wheel to scroll up or down (looking for a second component to select), it will zoom in and out the graphics window instead of scrolling the design tree. One thing that I find odd about it, is that it only does it on some assemblies, but not all of them. To my knowledge, all the assemblies I have used are created the same. I have also created two independent assemblies (using the same assembly templates) where one has this problem while the other does not. And it does not seem to matter what size the assembly is. It happens to both large and small assemblies.