diff --git a/src/store/index.ts b/src/store/index.ts
index 67466bd..c921912 100644
--- a/src/store/index.ts
+++ b/src/store/index.ts
@@ -256,6 +256,8 @@ export const storeKey: InjectionKey<VuexStore<StateInterface>> =
   Symbol("vuex-key");
 
 import window_color_list from "./window_color_list.js";
+const NullSignalSource =
+  "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF";
 
 export default store(function (/* { ssrContext } */) {
   const Store = createStore<StateInterface>({
@@ -737,7 +739,11 @@ export default store(function (/* { ssrContext } */) {
         state.selected_window = playload;
       },
       setSelectedSignalSource(state: StateInterface, playload?: any) {
-        state.selected_signal_source = playload;
+        if (state.selected_signal_source == playload) {
+          state.selected_signal_source = NullSignalSource;
+        } else {
+          state.selected_signal_source = playload;
+        }
       },
       setCurrentRunningPlan(state: StateInterface, playload?: any) {
         state.current_running_plan = playload;