Mac App Store application's Update window is weird
Some months ago I noticed that the appearance of the App Store's Update window completely changed. I thought it might have been due to a recent OS update. But the more I look at it the more inclined I am to think something is wrong with the display.
I'm running macOS 10.13.6 and the App Store app is version 2.4. Does anyone else's window look like this?
MacBook Pro 15″, OS X 10.11