Get the _NET_STARTUP_ID in manage_window, get the corresponding workspace

include/atoms.xmacro

@@ -15,6 +15,7 @@ xmacro(_NET_CLIENT_LIST_STACKING)
 xmacro(_NET_CURRENT_DESKTOP)
 xmacro(_NET_ACTIVE_WINDOW)
 xmacro(_NET_WORKAREA)
+xmacro(_NET_STARTUP_ID)
 xmacro(WM_PROTOCOLS)
 xmacro(WM_DELETE_WINDOW)
 xmacro(UTF8_STRING)

include/startup.h

@@ -32,4 +32,15 @@ void start_application(const char *command);
  */
 void startup_monitor_event(SnMonitorEvent *event, void *userdata);
 
+/**
+ * Checks if the given window belongs to a startup notification by checking if
+ * the _NET_STARTUP_ID property is set on the window (or on its leader, if it’s
+ * unset).
+ *
+ * If so, returns the workspace on which the startup was initiated.
+ * Returns NULL otherwise.
+ *
+ */
+char *startup_workspace_for_window(i3Window *cwindow, xcb_get_property_reply_t *startup_id_reply);
+
 #endif