Handle _NET_CLOSE_WINDOW client message requests

> Pagers wanting to close a window MUST send a _NET_CLOSE_WINDOW client
> message request to the root window.

We interpret this message as a request to close the con for the given
window.

See: http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#idm140200472668896

fixes #1396

include/atoms.xmacro

@@ -20,6 +20,7 @@ xmacro(_NET_NUMBER_OF_DESKTOPS)
 xmacro(_NET_DESKTOP_NAMES)
 xmacro(_NET_DESKTOP_VIEWPORT)
 xmacro(_NET_ACTIVE_WINDOW)
+xmacro(_NET_CLOSE_WINDOW)
 xmacro(_NET_STARTUP_ID)
 xmacro(_NET_WORKAREA)
 xmacro(WM_PROTOCOLS)

src/ewmh.c

@@ -234,5 +234,5 @@ void ewmh_setup_hints(void) {
     /* I’m not entirely sure if we need to keep _NET_WM_NAME on root. */
     xcb_change_property(conn, XCB_PROP_MODE_REPLACE, root, A__NET_WM_NAME, A_UTF8_STRING, 8, strlen("i3"), "i3");
 
-    xcb_change_property(conn, XCB_PROP_MODE_REPLACE, root, A__NET_SUPPORTED, XCB_ATOM_ATOM, 32, 22, supported_atoms);
+    xcb_change_property(conn, XCB_PROP_MODE_REPLACE, root, A__NET_SUPPORTED, XCB_ATOM_ATOM, 32, 23, supported_atoms);
 }

src/handlers.c

@@ -838,6 +838,24 @@ static void handle_client_message(xcb_client_message_event_t *event) {
                 ++idx;
             }
         }
+    } else if (event->type == A__NET_CLOSE_WINDOW) {
+        /*
+         * Pagers wanting to close a window MUST send a _NET_CLOSE_WINDOW
+         * client message request to the root window.
+         * http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#idm140200472668896
+         */
+        Con *con = con_by_window_id(event->window);
+        if (con) {
+            DLOG("Handling _NET_CLOSE_WINDOW request (con = %p)\n", con);
+
+            if (event->data.data32[0])
+                last_timestamp = event->data.data32[0];
+
+            tree_close(con, KILL_WINDOW, false, false);
+            tree_render();
+        } else {
+            DLOG("Couldn't find con for _NET_CLOSE_WINDOW request. (window = %d)\n", event->window);
+        }
     } else {
         DLOG("unhandled clientmessage\n");
         return;

testcases/t/239-net-close-window-request.t

@@ -0,0 +1,49 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Test _NET_CLOSE_WINDOW requests to close a window.
+# See http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#idm140200472668896
+# Ticket: #1396
+# Bug still in: 4.8-116-gbb1f857
+use i3test;
+
+sub send_close_window_request {
+    my ($win) = @_;
+
+    my $msg = pack "CCSLLLLLL",
+        X11::XCB::CLIENT_MESSAGE, # response_type
+        32, # format
+        0, # sequence
+        $win->id, # window
+        $x->atom(name => '_NET_CLOSE_WINDOW')->id, # message type
+        0, # data32[0]
+        0, # data32[1]
+        0, # data32[2]
+        0, # data32[3]
+        0; # data32[4]
+
+    $x->send_event(0, $x->get_root_window(), X11::XCB::EVENT_MASK_SUBSTRUCTURE_REDIRECT, $msg);
+}
+
+my $ws = fresh_workspace;
+my $win = open_window;
+
+send_close_window_request($win);
+sync_with_i3;
+
+is(@{get_ws($ws)->{nodes}}, 0, 'When a pager sends a _NET_CLOSE_WINDOW request for a window, the container should be closed');
+
+done_testing;