This evening, another bug was discovered in the new OgreKit. I suspect this bug was reported earlier when I wasn't paying attention, but luckily another user reported it after dinner. If you "Find All" in the new OgreKit, the operation works fine. But after that, the source editor will not accept changes. The user can type, but no new text appears in the source. HOWEVER, if you close the source file and then reopen it, the new typing is there. So the file before saving and the file after reopening are different. This is unacceptable.
Consequently, I have released TeXShop 4.17 which reverts OgreKit back to the earlier version. This version has minor font size bugs and Dark Mode bugs, but no serious problems. TeXShop 4.17 again runs on Yosemite and has all other changes in 4.16 except a revised OgreKit.
In the future, we will not release a TeXShop with an up to date OgreKit before subjecting it to serious testing.