Bugfix: Correctly restore the focus to the root screen after unmapping the last client (Thanks Rasi)

Sometimes, it may happen that the focus is "nowhere" and thus the
user is stuck. This was often the case with opera, sometimes with
pcmanfm. See ticket #118.

src/handlers.c

@@ -501,9 +501,19 @@ int handle_unmap_notify_event(void *data, xcb_connection_t *conn, xcb_unmap_noti
 
         render_layout(conn);
 
-        /* Ensure the focus is set to the next client in the focus stack */
+        /* Ensure the focus is set to the next client in the focus stack or to
-        if (workspace_active && to_focus != NULL)
+         * the screen itself (if we do not focus the screen, it can happen that
+         * the focus is "nowhere" and thus keypress events will not be received
+         * by i3, thus the user cannot use any hotkeys). */
+        if (workspace_active) {
+                if (to_focus != NULL)
                         set_focus(conn, to_focus, true);
+                else {
+                        LOG("Restoring focus to root screen\n");
+                        xcb_set_input_focus(conn, XCB_INPUT_FOCUS_POINTER_ROOT, root, XCB_CURRENT_TIME);
+                        xcb_flush(conn);
+                }
+        }
 
         return 1;
 }