Implement force state for features like in the proposal

src/components/views/settings/tabs/user/LabsUserSettingsTab.js

@@ -35,7 +35,8 @@ export class LabsSettingToggle extends React.Component {
     render() {
         const label = SettingsStore.getDisplayName(this.props.featureId);
         const value = SettingsStore.getValue(this.props.featureId);
-        return <LabelledToggleSwitch value={value} label={label} onChange={this._onChange} />;
+        const canChange = SettingsStore.canSetValue(this.props.featureId, null, SettingLevel.DEVICE);
+        return <LabelledToggleSwitch value={value} label={label} onChange={this._onChange} disabled={!canChange} />;
     }
 }
 

src/settings/SettingsStore.ts

@@ -23,7 +23,6 @@ import AccountSettingsHandler from "./handlers/AccountSettingsHandler";
 import RoomSettingsHandler from "./handlers/RoomSettingsHandler";
 import ConfigSettingsHandler from "./handlers/ConfigSettingsHandler";
 import { _t } from '../languageHandler';
-import SdkConfig from "../SdkConfig";
 import dis from '../dispatcher/dispatcher';
 import { ISetting, SETTINGS } from "./Settings";
 import LocalEchoWrapper from "./handlers/LocalEchoWrapper";
@@ -435,6 +434,12 @@ export default class SettingsStore {
             throw new Error("Setting '" + settingName + "' does not appear to be a setting.");
         }
 
+        // When features are specified in the config.json, we force them as enabled or disabled.
+        if (SettingsStore.isFeature(settingName)) {
+            const configVal = SettingsStore.getValueAt(SettingLevel.CONFIG, settingName, roomId, true, true);
+            if (configVal === true || configVal === false) return false;
+        }
+
         const handler = SettingsStore.getHandler(settingName, level);
         if (!handler) return false;
         return handler.canSetValue(settingName, roomId);