Do you mean highlighting like this?
If that's what you mean, you can turn it off in Preferences > Advanced Type > Uncheck Type Contextual Controls: Show for Alternates.
If that's not what you mean, make a screen capture and attach it with the "camera" icon in the editing window. (Don't try to send by email.)
That isn't what was happening. Adobe support fixed my issue of boxes, however not the issue of the black screen flash.
Are you using multiple monitors? There appears to be a bug in El Capitan with InDesign when there are multiple monitors (reported in another thread).
Nope. Just a brand spankin new iMac.