Don't do it. I use to work as a PC technician and I tried to stay away from editing the registry if that gives you an idea of how touchy it is. You put a period in the wrong place and can break your whole OS. I will say however that if you do break your OS, go to a Microsoft Store and they can fix it for free. Just be willing to probably part with your computer for a week or so.
Yeah... I wouldn't mess around with the registry unless you really know what you are doing. As for Windows 10. I haven't used a PC much at all for over a decade. I've done my share of fixing my friends systems when they mess them up however. At work we use IBM Power stuff with a proprietary Unix underpinning and at home I use Mac Hardware with Ubuntu. I need Unix for the stuff I program for work. For recreational use I will use the Mac OS on my tower.
As a computer hobbiest I completely agree, I may use a registery cleaner from time to time on older comps, that is risky too, but never manually edit it. As for 10, using it on my main laptop, and on my 8 inch dell tablet. A few bugs here and there that require a reboot, but generally smoother and faster than win 10, and much more favorable than 8.1...
Just a follow up, I did the registry thing a few weeks ago and everything is fine. I didn't manually edit anything as the link I posted lets you download 2 registry edits. One that changes windows to the hidden dark theme and one that will undo that change. I talked to my buddy and showed him the edit files and he said they were safe. Thanks for the advice though, I'll stay clear of registry stuff.