dwm

 1/* cc transient.c -o transient -lX11 */
 2
 3#include <stdlib.h>
 4#include <unistd.h>
 5#include <X11/Xlib.h>
 6#include <X11/Xutil.h>
 7
 8int main(void) {
 9	Display *d;
10	Window r, f, t = None;
11	XSizeHints h;
12	XEvent e;
13
14	d = XOpenDisplay(NULL);
15	if (!d)
16		exit(1);
17	r = DefaultRootWindow(d);
18
19	f = XCreateSimpleWindow(d, r, 100, 100, 400, 400, 0, 0, 0);
20	h.min_width = h.max_width = h.min_height = h.max_height = 400;
21	h.flags = PMinSize | PMaxSize;
22	XSetWMNormalHints(d, f, &h);
23	XStoreName(d, f, "floating");
24	XMapWindow(d, f);
25
26	XSelectInput(d, f, ExposureMask);
27	while (1) {
28		XNextEvent(d, &e);
29
30		if (t == None) {
31			sleep(5);
32			t = XCreateSimpleWindow(d, r, 50, 50, 100, 100, 0, 0, 0);
33			XSetTransientForHint(d, t, f);
34			XStoreName(d, t, "transient");
35			XMapWindow(d, t);
36			XSelectInput(d, t, ExposureMask);
37		}
38	}
39
40	XCloseDisplay(d);
41	exit(0);
42}