main.c

#include <stdio.h>
#include <stddef.h>
#include <X11/Xlib.h>
#include <assert.h>
#include <unistd.h>
#include <signal.h>


int working = 1;

void signal_callback_handler(int signum) {
    working = 0;
}

int main () {
    signal(SIGINT, signal_callback_handler);
    signal(SIGTSTP, signal_callback_handler);
    signal(SIGTERM, signal_callback_handler);

    Display *d = XOpenDisplay(NULL);
    assert(d);

    XSelectInput(d, DefaultRootWindow(d), ButtonPressMask);
    while(working) {
        XEvent e;
        XNextEvent(d,&e);
        if (e.type == ButtonPress) {
            printf("%dx%d",e.xbutton.x,e.xbutton.y);
        }
    }


    return 0;
}

X Error of failed request: BadAccess (attempt to access private resource denied)
Major opcode of failed request: 2 (X_ChangeWindowAttributes)
Serial number of failed request: 7
Current serial number in output stream: 7