Ok I have the Hwnd to a particular window I want to work with.
Lets call this windows program the "UNWANTED".

This UNWANTED window has two things I wish to identify it by.
The first one I already have.. which is it's windows handle!
Second.. is what I need to obtain which is the metrics for the window. E.g Width\Height .. I need this first..

SO after I have the metrics for the window lets just say it's 200x, 200y I will write a program that finds this UNWANTED window by title as I already know the title, and will use hwnd = FindWindow("title etc.."); So I will have the Hwnd!
Now My program will need to test for the metrics.. IF this window has 200x, 200y metrics then send WM_DESTROY for this UNWANTED program.

So 1 program gets the metrics which I will hardcode into the Second program that looks for a window that has those matching metrics and closes it!

GetSystemMatrics() works for the display monitor only. You have to call other win32 api functions to get the informatgion you want. To get the window's height/width call GetWindowRect()

char AncientDragon = TheBomb();