Created attachment 362728 [details]
bug with new tab button
New bug found, probably concerns layout and rendering of the elements in Safari for Mac (please see screenshot attached).
One more (inactive) "new tab button" appears under specific conditions.
A situation that created this bug: I was working on 2 screens with my Mac connected to TV (safari was opened on TV), then I put Mac to sleep without unplugging the HDMI, next morning I unplugged Mac from HDMI without turning on the Mac, and once I opened my Mac in college I noticed this small bug.
This is a Safari bug, not a WebKit bug. Please report at bugreport.apple.com