[4.17.2] Why does my GetViewportSize Node return inaccurate results? [Solved?]

Ive called a GetViewportSize Node and use the results to draw a square around what is suppose to be the edges of the game window using the Draw Line Node in the OnPaint Event. But the lines draw a square that is significantly smaller than the the game window.

What could be causing this and what do I need to do to get the Size of the Game Window?

Maybe you have to multiply ut by screen dpi. There should be a get nide for that.

I solved it by completely flattening the DPI Curve in Project Settings > User Interface > DPI Curve I deleted all the points on the curve and then add two new points.
One at 800, 1.0 and one at 8192, 1.0. This has resulted in my drawn lines exactly matching the game screen regardless of its size.

That said, Im a bit worried about this solution. Is DPI scaling all that important?
And if, as my results suggest, a flat DPI Curve is best then why is the default setting not flat?