Windows 10: Unwanted Black Transparent Box in Bottom Right Corner

After pressing multiple keys on the keyboard at the same time (near the left side) this unwanted box in the bottom right corner appeared on my monitors. I have closed all apps in the task manager and restarted multiple times. I think it has to do with display settings because when I tried to take a screenshot of the box it wouldn't show up in the picture. I am also sure it is not due to monitor settings because I have 3 different types of monitors and the box is in the same corner on each monitor.


Thank you for your help.

:)

 

Unwanted transparent box in corner of screen


This is the same section of my Edge on a Notebook with Win10 Version 1803 Build 17134.112 [latest], doesn't have that box with the star:



Could it be a third-party add-on/extension doing it?
Also, it doesn't show in Firefox.

 

Unwanted transparent box in corner of screen


I have an unwanted transparent box that has recently appeared in the top right hand corner of my screen
I is always there irrespective of what program I am using
Clicking on it does nothing and I cant drag it
I am using Bitdefender antivirus and a full system scan has not shown any problem
When I try to print the screen the box doesn't show so I have attached a photo showing it
Any advice on what it is and how to remove it would be appreciated

 

Unwanted transparent box in corner of screen


Hi Guru
Clicking on the star with the three bars just opens my favourite web page list
Then clicking on Favourites Bar does nothing
But I have just noticed that when I reduce the size of the Edge window the transparent box disappears and then reappears when I enlarge the window