Screen save part
From GMWiki, the Gamemaker Wiki.
void screen_save_part(fname,x,y,w,h)
Saves a bmp image of a region of the screen, starting at position x, y and with the width w and height h, to the file fname.
Saves a bmp image of a region of the screen, starting at position x, y and with the width w and height h, to the file fname.