add xgetnewwindow, which waits the creation of a new window in the xorg server

c/xgetnewwindow.c

@@ -0,0 +1,29 @@
+#include <X11/Xlib.h>
+#include <stdio.h>
+
+int main(void) {
+	Display* display = XOpenDisplay(NULL);
+	if(!display) {
+		printf("Error: Unable to open display.\n");
+		return 1;
+	}
+
+	int screen = DefaultScreen(display);
+	Window root = RootWindow(display, screen);
+
+	/* SubstructureNotifyMask allows us to be notified of CreateNotify events */
+	XSelectInput(display, root, SubstructureNotifyMask);
+
+	XEvent event;
+	for(;;) {
+		XNextEvent(display, &event);
+		if(event.type == CreateNotify) {
+			/* print window id */
+			printf("0x%x\n", event.xcreatewindow.window);
+			break;
+		}
+	}
+
+	XCloseDisplay(display);
+	return 0;
+}

man/xgetnewwindow.1

@@ -0,0 +1,10 @@
+.TH XGETNEWWINDOW 1 xgetnewwindow
+.SH NAME
+xgetnewwindow
+.SH SYNOPSIS
+xgetnewwindow blocks until it recieves a CreateNotify event; that is, until a new window is created within the current Xorg instance. Once a new window is created, xgetnewwindow prints the window id (in hexadecimal) to stdout and exits.
+.SH EXIT CODES
+1 for abnormal termination, 0 for success.
+.SH AUTHOR
+randomuser
+