core: 窗口分层类型与接口草案

src/core/policy.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include "core/layer.h"
+#include "core/state.h"
+#include "core/types.h"
+
+layer_type_t policy_adjust_window_layer_from_transient(
+  const state_t *state, window_id_t transient_for, layer_type_t base_layer);