Display *dpy;
Window w;

void init_window() {
unsigned long white = WhitePixel(dpy, DefaultScreen(dpy));
w = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, 100, 100, 0, white, white);
}

void pset(int x, int y) {
XDrawPixel(dpy, w, x, y);
}