[Update] Combine in one window. Rename Main/Config Window to Main/Config Page accordingly.

For now, I put Config Page to below the main page temporary. Open Config Button does not work.

src-ui/app/main_page/main_section/MainSection.jsx

@@ -0,0 +1,30 @@
+import styles from "./MainSection.module.scss";
+
+import { TopBar } from "./top_bar/TopBar";
+import { MessageContainer } from "./message_container/MessageContainer";
+import { LanguageSelector } from "./language_selector/LanguageSelector";
+
+import { useIsOpenedLanguageSelector } from "@store";
+
+export const MainSection = () => {
+
+    return (
+        <div className={styles.container}>
+            <TopBar />
+            <MessageContainer />
+            <HandleLanguageSelector />
+        </div>
+    );
+};
+
+const HandleLanguageSelector = () => {
+    const { currentIsOpenedLanguageSelector } = useIsOpenedLanguageSelector();
+
+    if (currentIsOpenedLanguageSelector.your_language === true) {
+        return <LanguageSelector id="your_language"/>;
+    } else if (currentIsOpenedLanguageSelector.target_language === true) {
+        return <LanguageSelector id="target_language"/>;
+    } else {
+        return null;
+    }
+};