Fix mobile SelectMultipleFilter.

It didn't call onSubmit after latest Final Form update was introduced to PR949.
(v2.9.0))

src/components/SelectMultipleFilter/SelectMultipleFilter.css

@@ -42,7 +42,30 @@
   }
 }
 
+.fieldGroup {
+  margin: 0;
+  padding: 0;
+  border: none;
+}
+
 .fieldGroupPlain {
+  margin: 0;
   padding-left: 20px;
   padding-bottom: 30px;
+  border: none;
+}
+
+.list {
+  margin: 0;
+}
+
+.item {
+  padding: 2px 0;
+
+  /* Fix broken multi-column layout in Chrome */
+  page-break-inside: avoid;
+
+  @media (--viewportMedium) {
+    padding: 4px 0;
+  }
 }

src/components/SelectMultipleFilter/SelectMultipleFilter.js

@@ -2,11 +2,32 @@ import React, { Component } from 'react';
 import { array, arrayOf, func, number, string } from 'prop-types';
 import classNames from 'classnames';
 import { injectIntl, intlShape } from 'react-intl';
-import { FieldCheckboxGroup } from '../../components';
+import { FieldCheckbox } from '../../components';
 
 import { FilterPopup, FilterPlain } from '../../components';
 import css from './SelectMultipleFilter.css';
 
+// SelectMultipleFilter doesn't need array mutators since it doesn't require validation.
+// TODO: Live edit didn't work with FieldCheckboxGroup
+//       There's a mutation problem: formstate.dirty is not reliable with it.
+const GroupOfFieldCheckboxes = props => {
+  const { id, className, name, options } = props;
+  return (
+    <fieldset className={className}>
+      <ul className={css.list}>
+        {options.map((option, index) => {
+          const fieldId = `${id}.${option.key}`;
+          return (
+            <li key={fieldId} className={css.item}>
+              <FieldCheckbox id={fieldId} name={name} label={option.label} value={option.key} />
+            </li>
+          );
+        })}
+      </ul>
+    </fieldset>
+  );
+};
+
 class SelectMultipleFilter extends Component {
   constructor(props) {
     super(props);
@@ -101,7 +122,7 @@ class SelectMultipleFilter extends Component {
         urlParam={urlParam}
         {...rest}
       >
-        <FieldCheckboxGroup
+        <GroupOfFieldCheckboxes
           className={css.fieldGroup}
           name={name}
           id={`${id}-checkbox-group`}
@@ -122,7 +143,7 @@ class SelectMultipleFilter extends Component {
         urlParam={urlParam}
         {...rest}
       >
-        <FieldCheckboxGroup
+        <GroupOfFieldCheckboxes
           className={css.fieldGroupPlain}
           name={name}
           id={`${id}-checkbox-group`}