Simple X11 program

gui.c

#include <X11/Xlib.h>

int main() {
        XEvent event;
        Display* display = XOpenDisplay(NULL);
        Window w = XCreateSimpleWindow(display, DefaultRootWindow(display), 50, 50, 250, 250, 1, BlackPixel(display, 0), WhitePixel(display, 0));
        XMapWindow(display, 0);
        XSelectInput(display, w, ExposureMask);

        for (;;) {
                XNextEvent(display, &event);
                if (event.type == Expose) {
                        XDrawString(display, w, DefaultGC(display, 0), 100, 100, "That's all folks!", 20);
                }
        }

        return 0;
}