Since upgrading to 10.12.6 Beta 6 (16G24b), certain apps have similar visual glitches where I see lots of rectangles with different colors, or sometimes all black.
Some areas I've noticed it:
- Messages, where the conversation appears (the side pane to select a user, and the text entry field at the bottom appear normal)
- Screen Sharing, where I see the remote desktop (the toolbar at the top of the window appears normal)
- Preview, where you see the document (the side pane where you can see a preview of a page appears normal)
Text looks especially strange in both Preview and Messages - I can sort of tell that the rectangles are making out letters but it's completely illegible.
rdar://33246839 if anyone internal is interested in my sysdiagnose