Mouse click on a specific position (gives focus to clicked window)

//https://www.x.org/releases/X11R7.5/doc/man/man3/XIWarpPointer.3.html
//https://www.x.org/releases/X11R7.5/doc/man/man3/XOpenDevice.3.html
//https://www.x.org/releases/X11R7.7/doc/libXi/inputlib.html
//http://osr507doc.sco.com/en/man/html.Xext/XTEST.Xext.html
//xinput: ⎜   ↳ mouse XTEST pointer                     	id=16	[slave  pointer  (14)]
// -> 14 XIWarpPointer; 16 XOpenDevice
//gcc -lXi -lX11 -lXtst -o test BackgroundMouse.c 
#include <X11/Xlib.h>
#include <X11/extensions/XInput2.h>
#include <X11/extensions/XTest.h>
int main (int argc, char *argv[])
{
  int delta_x = 500, delta_y = 160;
  Display *display = XOpenDisplay(0);
  Window root = DefaultRootWindow(display);
  XIWarpPointer(display, 14, None, root, 0, 0, 0, 0, delta_x, delta_y);
  XDevice *device = NULL;
  device = XOpenDevice(display, 16);
  XTestFakeDeviceButtonEvent(display, device, 1, True, 0, 0, CurrentTime);
  XTestFakeDeviceButtonEvent(display, device, 1, False, 0, 0, CurrentTime);
  XCloseDisplay(display);
}