some minor modifications

src/index.js

@@ -1,18 +1,31 @@
-import React from "react";
+import React, { useState } from "react";
 import ReactDOM from "react-dom/client";
 import CircularProgress from "@mui/material/CircularProgress";
 import Divider from "@mui/material/Divider";
 import ReactMarkdown from "react-markdown";
 import Paper from "@mui/material/Paper";
+import Stack from "@mui/material/Stack";
+import Button from "@mui/material/Button";
 import { useFetch } from "./hooks/Fetch";
 import { I18N, URL_RAW_PREFIX } from "./config";
 
 function App() {
+  const [lang, setLang] = useState("zh");
   const [data, loading, error] = useFetch(
-    `${URL_RAW_PREFIX}/${I18N?.["about_md"]?.["zh"]}`
+    `${URL_RAW_PREFIX}/${I18N?.["about_md"]?.[lang]}`
   );
   return (
     <Paper sx={{ padding: 2, margin: 2 }}>
+      <Stack spacing={2} direction="row" justifyContent="flex-end">
+        <Button
+          variant="text"
+          onClick={() => {
+            setLang((pre) => (pre === "zh" ? "en" : "zh"));
+          }}
+        >
+          {lang === "zh" ? "ENGLISH" : "中文"}
+        </Button>
+      </Stack>
       <Divider>{`KISS Translator v${process.env.REACT_APP_VERSION}`}</Divider>
       {loading ? (
         <center>

src/userscript.js

@@ -6,6 +6,7 @@ import { CacheProvider } from "@emotion/react";
 import { getSetting, getRules, matchRule, getFab } from "./libs";
 import { Translator } from "./libs/translator";
 import { trySyncAllSubRules } from "./libs/rules";
+import { isGm } from "./libs/browser";
 
 /**
  * 入口函数
@@ -57,6 +58,7 @@ import { trySyncAllSubRules } from "./libs/rules";
   );
 
   // 注册菜单
+  if (isGm) {
     GM.registerMenuCommand(
       "Toggle Translate",
       (event) => {
@@ -71,6 +73,7 @@ import { trySyncAllSubRules } from "./libs/rules";
       },
       "C"
     );
+  }
 
   // 同步订阅规则
   trySyncAllSubRules(setting);

src/views/Options/Rules.js

@@ -638,6 +638,7 @@ function SubRulesEdit({ subrules }) {
   const [inputText, setInputText] = useState("");
   const [inputError, setInputError] = useState("");
   const [showInput, setShowInput] = useState(false);
+  const [loading, setLoading] = useState(false);
 
   const handleCancel = (e) => {
     e.preventDefault();
@@ -661,6 +662,7 @@ function SubRulesEdit({ subrules }) {
     }
 
     try {
+      setLoading(true);
       const rules = await syncSubRules(url);
       if (rules.length === 0) {
         throw new Error("empty rules");
@@ -671,6 +673,8 @@ function SubRulesEdit({ subrules }) {
     } catch (err) {
       console.log("[fetch rules]", err);
       setInputError(i18n("error_fetch_url"));
+    } finally {
+      setLoading(false);
     }
   };
 
@@ -713,7 +717,12 @@ function SubRulesEdit({ subrules }) {
           />
 
           <Stack direction="row" alignItems="center" spacing={2}>
-            <Button size="small" variant="contained" onClick={handleSave}>
+            <Button
+              size="small"
+              variant="contained"
+              onClick={handleSave}
+              disabled={loading}
+            >
               {i18n("save")}
             </Button>
             <Button size="small" variant="outlined" onClick={handleCancel}>