GetWindowRect has offset in Windows 10

Question

I use GetWindowRect in my program to get the coordinates of a window on the desktop. This works fine on a dozen or so PCs I have here for testing (XP-W8.1) but not on my one

Answer 1

Your program is not DPI aware and so is subject to DPI virtualization. That means that the coordinates returned by functions like GetWindowRect will be virtualized coordinates and so will not match the true screen coordinates.