what is gdi?
sometihng to do with drawing or painting in windows lol

a good example

#include <windows.h> //WINDOWS FTW
#include <iostream.h> //cout,cin all that jazz
int main()
{
HWND window // window handle named window rofl
HDC devcon //deviceContext handlenamed devcon rofl again :)
window = FindWindow(NULL,"Window Title Here"); //finds a window with that title
devcon = GetDC(window); //tell devcon where the context is
SetTextColor(devcon,RGB(0,0,0)); //set our text color to black
TextOut(devcon,1,1, 'Yay im text on a Window W00t',30); //print thy text
UpdateWindow(window); //update the window
ReleaseDC(window,devcon); //ALWAYS RELAESE TO PREVENT MEMORY LEAKS
}

that should help some pplz