Xlib mouse events and ButtonPressMask

Question

I have written a simple program which will report key press and release events for a particular window. In my case, it is mostly the terminal since I invoke the program from the terminal. I am able to get the key press and release events taking place in the terminal window (I have used XSelectInput() with KeyPressMask and KeyReleaseMask on the terminal) but the same is not working with ButtonPress and ButtonRelease. Not just these, but any events related to the mouse are not being reported. Any idea why this is happening?

#include
#include
#include
#include
#include
#include

int main() {
Display *display = XOpenDisplay(NULL);
KeySym k;
int revert_to;
Window window;
XEvent event;

XGetInputFocus(display, &window, &revert_to);
XSelectInput(display, window, KeyPressMask | KeyReleaseMask | ButtonPressMask | ButtonReleaseMask);

while(1)
{
XNextEvent(display,&event);
  switch (event.type) {

  case KeyPress : printf("Key Pressed\n"); break;
  case KeyRelease : printf("Key Released\n"); break;
  case ButtonPress : printf("Button Pressed\n"); break;
  case ButtonRelease : printf("Button Released\n"); break;
  case EnterNotify : printf("Enter\n"); break;
  }
}
XCloseDisplay(display);
return 0;
}

Answer 1

The problem you encounter is that Xlib sends ButtonPress/Release events to only one client. I think that the window you're working with already has a client which is listening to its mouse events. Therefore your SelectInput call did not actually set ButtonPress/Release masks and generated an error which you didn't check for.