my global .gitignore excluded this file ;_;

app/javascript/flavours/glitch/features/composer/textarea/icons/index.js

@@ -0,0 +1,60 @@
+//  Package imports.
+import PropTypes from 'prop-types';
+import React from 'react';
+import ImmutablePropTypes from 'react-immutable-proptypes';
+import { defineMessages } from 'react-intl';
+
+//  Components.
+import Icon from 'flavours/glitch/components/icon';
+
+//  Messages.
+const messages = defineMessages({
+  localOnly: {
+    defaultMessage: 'This post is local-only',
+    id: 'advanced_options.local-only.tooltip',
+  },
+  threadedMode: {
+    defaultMessage: 'Threaded mode enabled',
+    id: 'advanced_options.threaded_mode.tooltip',
+  },
+});
+
+//  We use an array of tuples here instead of an object because it
+//  preserves order.
+const iconMap = [
+  ['do_not_federate', 'home', messages.localOnly],
+  ['threaded_mode', 'comments', messages.threadedMode],
+];
+
+//  The component.
+export default function ComposerTextareaIcons ({
+  advancedOptions,
+  intl,
+}) {
+
+  //  The result. We just map every active option to its icon.
+  return (
+    <div className='composer--textarea--icons'>
+      {advancedOptions ? iconMap.map(
+        ([key, icon, message]) => advancedOptions.get(key) ? (
+          <span
+            className='textarea_icon'
+            key={key}
+            title={intl.formatMessage(message)}
+          >
+            <Icon
+              fullwidth
+              icon={icon}
+            />
+          </span>
+        ) : null
+      ) : null}
+    </div>
+  );
+}
+
+//  Props.
+ComposerTextareaIcons.propTypes = {
+  advancedOptions: ImmutablePropTypes.map,
+  intl: PropTypes.object.isRequired,
+};