Question Obtaining scaled display size (+ multi monitor offset) for editor code

I want to center some custom editor windows on the screen. I'm having trouble getting the correct display dimensions. Consider this general pseudo-ish code:

Code (CSharp):

1. int DialogWidth = 500;
2. int DialogHeight = 400;
3. int DisplayWidth = ...;
4. int DisplayHeight = ...;
5.  
6. // And desired window rect is calculated as:
7. _ = new Rect((DisplayWidth - DialogWidth) / 2,
8.              (DisplayHeight - DialogHeight) / 2,
9.              DialogWidth,
10.              DialogHeight);

So, for the display dimensions, my initial naïve attempt was:

Code (CSharp):

1. int DisplayWidth = Screen.width;
2. int DisplayHeight = Screen.height;

Of course that didn't work because that's the size of the game area, not the actual display. So then I tried:

Code (CSharp):

1. int DisplayWidth = Screen.currentResolution.width;
2. int DisplayHeight = Screen.currentResolution.height;

That still wasn't right but, my system scaling is set to 250% and the editor is set to use system scaling, so hypothesizing that scaling was the issue I tried:

Code (CSharp):

1. int DisplayWidth = (int)(Screen.currentResolution.width / 2.5);
2. int DisplayHeight = (int)(Screen.currentResolution.height / 2.5);

And it worked perfectly, confirming scale factor as the issue.

But that's not a good solution, I need to be able to do that calculation without hard coding a scale factor so that it works in any environment. So, my first question is:

Q: How can I get the scaled display size in an editor script?

The other thing is, I want this to also work on multiple monitor setups, but I don't actually have a setup right now to experiment with. So the second question is:

Q: How can I get the offset and scaled display size for the monitor that the Unity Editor is currently being displayed on?

Thanks!

Note: I am actually also interested in other ways to center dialogs; but regardless I would like to find out how to get the correct display size in case I ever need it for something else some day (plus I'd still be curious). So getting display size is still my primary question, even if I don't need it for centering dialogs.