#include <X11/Xlib.h>
#include <unistd.h>
int main() {
Display *dpy = XOpenDisplay(NULL);
if (dpy == NULL) fprintf(stderr, "Could not open X display!\n"), exit(1);
int blackColor = BlackPixel(dpy, DefaultScreen(dpy));
int whiteColor = WhitePixel(dpy, DefaultScreen(dpy));
Window w = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy), 0, 0, 200, 100, 0, blackColor, blackColor);
XSelectInput(dpy, w, StructureNotifyMask);
XMapWindow(dpy, w);
GC gc = XCreateGC(dpy, w, 0, NULL);
XSetForeground(dpy, gc, whiteColor);
for(;;) {
XEvent e;
XNextEvent(dpy, &e);
if (e.type == MapNotify) break;
}
XDrawLine(dpy, w, gc, 10, 60, 180, 20);
XFlush(dpy);
sleep(10);
}