You do not need to use existing coordinates for both the X and Y portions of the coordinate. For example, you can construct an X,Y coordinate by using the Y coordinate of an existing line and picking the X coordinate anywhere on the screen.
Obstoječih koordinat vam ni treba uporabiti tako za koordinato x kot tudi za koordinato y. Koordinati x, y lahko, denimo, sestavite tako, da uporabite koordinato y obstoječe daljice, koordinato x pa izberete kjer koli na zaslonu.