Graph Builder: Add 1:1 Line

[#1]

Does anyone know how to add a 1:1 line to Graph Builder?  In the platform Fit Y by X there was a way to both fit the displayed data and show a 1:1 line.  I can't find how to do that in GB.  Thanks.

[#2]

gotcha, need to put 0.97x, x and 1.03x, x

[#3]

1:1 line - now available at a single mouse click via Graph Builder Toolbar :