XLib: 'Soft-Closing' a window

Question

I know, that I can 'close' an X11 Window by calling:

XDestroyWindow(display, id);

The problem is, this destroyes the window immediately. On the other hand, if i click the close button (x in the title bar) the app can show something like "Do you really want to exit?".

So how can I emulate this type of window closing?

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Background: I am closing windows from other applications, not my own

Answer 1

I found a solution:

XEvent event;
event.xclient.type = ClientMessage;
event.xclient.window = id;
event.xclient.message_type = XInternAtom(d, "WM_PROTOCOLS", TRUE);
event.xclient.format = 32;
event.xclient.data.l[0] = XInternAtom(d, "WM_DELETE_WINDOW", FALSE);
event.xclient.data.l[1] = CurrentTime;
XSendEvent(d, id, False, NoEventMask, &event);

Where d is the display handle and id is the window ID.

CREDIT: https://john.nachtimwald.com/2009/11/08/sending-wm_delete_window-client-messages/

Answer 2

It can be the same as stackoverflow.com/questions/1157364/intercept-wm-delete-window-on-x11