Merge branch 'threecolumn' into 'develop'

Layout refactoring + Three column mode

See merge request pleroma/pleroma-fe!1503

src/modules/config.js

@@ -50,6 +50,7 @@ export const defaultState = {
   pauseOnUnfocused: true,
   stopGifs: true,
   replyVisibility: 'all',
+  thirdColumnMode: 'notifications',
   notificationVisibility: {
     follows: true,
     mentions: true,
@@ -78,6 +79,8 @@ export const defaultState = {
   playVideosInModal: false,
   useOneClickNsfw: false,
   useContainFit: true,
+  disableStickyHeaders: false,
+  showScrollbars: false,
   greentext: undefined, // instance default
   useAtIcon: undefined, // instance default
   mentionLinkDisplay: undefined, // instance default
@@ -169,6 +172,9 @@ const config = {
           messages.setLanguage(this.getters.i18n, value)
           Cookies.set(BACKEND_LANGUAGE_COOKIE_NAME, localeService.internalToBackendLocale(value))
           break
+        case 'thirdColumnMode':
+          dispatch('setLayoutWidth', undefined)
+          break
       }
     }
   }