tests: Add 'can_take_focus' command to runner and client

Allow to set/unset WM_TAKE_FOCUS from client window.
This is added by default by gtk, but this might not happen in other toolkits,
so add an ability to (un)set this.

So fetch the protocols with XGetWMProtocols and unset the atom.

test-client now needs to depend on Xlib directly in meson build.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/307
(cherry picked from commit f2d2d473b7)

src/tests/test-client.c

@@ -179,6 +179,56 @@ process_line (const char *line)
       gboolean enabled = g_ascii_strcasecmp (argv[2], "true") == 0;
       gtk_window_set_accept_focus (GTK_WINDOW (window), enabled);
     }
+  else if (strcmp (argv[0], "can_take_focus") == 0)
+    {
+      if (argc != 3)
+        {
+          g_print ("usage: %s <window-id> [true|false]", argv[0]);
+          goto out;
+        }
+
+      GtkWidget *window = lookup_window (argv[1]);
+      if (!window)
+        {
+          g_print ("unknown window %s", argv[1]);
+          goto out;
+        }
+
+      if (wayland)
+        {
+          g_print ("%s not supported under wayland", argv[0]);
+          goto out;
+        }
+
+      GdkDisplay *display = gdk_display_get_default ();
+      GdkWindow *gdkwindow = gtk_widget_get_window (window);
+      Display *xdisplay = gdk_x11_display_get_xdisplay (display);
+      Window xwindow = GDK_WINDOW_XID (gdkwindow);
+      Atom wm_take_focus = gdk_x11_get_xatom_by_name_for_display (display, "WM_TAKE_FOCUS");
+      gboolean add = g_ascii_strcasecmp(argv[2], "true") == 0;
+      Atom *protocols = NULL;
+      Atom *new_protocols;
+      int n_protocols = 0;
+      int i, n = 0;
+
+      gdk_display_sync (display);
+      XGetWMProtocols (xdisplay, xwindow, &protocols, &n_protocols);
+      new_protocols = g_new0 (Atom, n_protocols + (add ? 1 : 0));
+
+      for (i = 0; i < n_protocols; ++i)
+        {
+          if (protocols[i] != wm_take_focus)
+            new_protocols[n++] = protocols[i];
+        }
+
+      if (add)
+        new_protocols[n++] = wm_take_focus;
+
+      XSetWMProtocols (xdisplay, xwindow, new_protocols, n);
+
+      XFree (new_protocols);
+      XFree (protocols);
+    }
   else if (strcmp (argv[0], "show") == 0)
     {
       if (argc != 2)

src/tests/test-runner.c

@@ -425,6 +425,25 @@ test_case_do (TestCase *test,
                            NULL))
         return FALSE;
     }
+  else if (strcmp (argv[0], "can_take_focus") == 0)
+    {
+      if (argc != 3 ||
+          (g_ascii_strcasecmp (argv[2], "true") != 0 &&
+           g_ascii_strcasecmp (argv[2], "false") != 0))
+        BAD_COMMAND("usage: %s <client-id>/<window-id> [true|false]",
+                    argv[0]);
+
+      TestClient *client;
+      const char *window_id;
+      if (!test_case_parse_window_id (test, argv[1], &client, &window_id, error))
+        return FALSE;
+
+      if (!test_client_do (client, error,
+                           argv[0], window_id,
+                           argv[2],
+                           NULL))
+        return FALSE;
+    }
   else if (strcmp (argv[0], "show") == 0 ||
            strcmp (argv[0], "hide") == 0 ||
            strcmp (argv[0], "activate") == 0 ||