Question: My kitten walked on my keyboard...
OS High Sierra.
If I am working in AOL or Gmail and I right click, the screen goes away to the right and I see the screen saver art with no icons ...nothing. I click again and It come back. I now have to hold teh control to actually right click. I went into preferences and clicked not original default settings and it does not help.
Not sure but this could have happened with up grade to High Sierra or when my cat Ralphie, walked across my keyboard while I was typing.
Any Ideas? And, no, Ralphie stays.
Mac mini, iOS 10.3.3