Comment 3 for bug 206837

As the upstream report refers to, Fitts law is the name for the principal violated. The upstream report also refers to the tab container as being a trigger. I can confirm this for Gnome Terminal - without tabs (a single term) the scroll bar is at screen edge when maximised, with 2 tabs the 1 pixel gap appears. Gedit always shows the tab control, even with only one document open. Hence the border is always there.

Attached is a screen shot to illustrate the problem.