2D Cockpit Windows

I have a three monitor setup, really cool however as you know I need to resize all of the @D cockpit windows dividing the first number by three not to difficult. My hard part is placing the window where I want it without having to move it around when I first open it. So far a lot of trial and error. So I am wondering isn't there a grid of the screen I can use to locate my window? I have a lot of numbers memorized now like I will place my GPS at 0.690, 0.575 which opens it up on the left screen lower left corner. If I had a grid in front of me showing the numbers up and over even in inches, centimeters anything would help. Kno where I might find something like that?

When I did something like that long ago I bought a clear plastic sheet at a stationary store and made the grid myself.