Settings toggle to disable Composer Markdown (#8358)

src/settings/Settings.tsx

@@ -133,7 +133,7 @@ export interface IBaseSetting<T extends SettingValueType = SettingValueType> {
     };
 
     // Optional description which will be shown as microCopy under SettingsFlags
-    description?: string;
+    description?: string | (() => ReactNode);
 
     // The supported levels are required. Preferably, use the preset arrays
     // at the top of this file to define this rather than a custom array.
@@ -611,6 +611,16 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         displayName: _td('Automatically replace plain text Emoji'),
         default: false,
     },
+    "MessageComposerInput.useMarkdown": {
+        supportedLevels: LEVELS_ACCOUNT_SETTINGS,
+        displayName: _td('Enable Markdown'),
+        description: () => _t(
+            "Start messages with <code>/plain</code> to send without markdown and <code>/md</code> to send with.",
+            {},
+            { code: (sub) => <code>{ sub }</code> },
+        ),
+        default: true,
+    },
     "VideoView.flipVideoHorizontally": {
         supportedLevels: LEVELS_ACCOUNT_SETTINGS,
         displayName: _td('Mirror local video feed'),

src/settings/SettingsStore.ts

@@ -16,6 +16,7 @@ limitations under the License.
 */
 
 import { logger } from "matrix-js-sdk/src/logger";
+import { ReactNode } from "react";
 
 import DeviceSettingsHandler from "./handlers/DeviceSettingsHandler";
 import RoomDeviceSettingsHandler from "./handlers/RoomDeviceSettingsHandler";
@@ -257,9 +258,11 @@ export default class SettingsStore {
      * @param {string} settingName The setting to look up.
      * @return {String} The description for the setting, or null if not found.
      */
-    public static getDescription(settingName: string) {
-        if (!SETTINGS[settingName]?.description) return null;
-        return _t(SETTINGS[settingName].description);
+    public static getDescription(settingName: string): string | ReactNode {
+        const description = SETTINGS[settingName]?.description;
+        if (!description) return null;
+        if (typeof description !== 'string') return description();
+        return _t(description);
     }
 
     /**