Screen woes

[JohnOne]

Is there a function to assign a certain pixel in a window as a reference point for all other coords ?

Ive found the checksum of a 10x10 pixel square, but dont really know what to do with it.

#include <Array.au3>

Sleep(3000)
$coord0 = PixelSearch(0, 0, 40, 145, 0x364C63)
If Not @error Then
    ;MouseMove($coord[0], $coord[1], 1)
    MsgBox(0, "X and Y are:", $coord[0] & "," & $coord[1])
    $checksum = PixelChecksum($coord0[0], $coord0[1], $coord0[0] + 10, $coord0[1] + 10)
    MsgBox(0, "", "$coord0 $checksum = " & $checksum)
EndIf

The window is scrollable you see so I cant use absolute screen coords.

I'm hoping its nothing to do with pixelcoordmode, as I dont quite understand that.

Is there a fuction for this ?

My goal is to move mouse to a coord on screen reletive to $coord0

Appreciate any hints