lang (and style) attribute doesn't change in live preview.
Steps to reproduce:
0. Make sure you're logged in.
- Click on cog to open ULS menu.
- In Display --> language tab, click on any language button other than English. Note down lang and style attributes of uls-display-settings class.
- Click Cancle.
- Reopen the menu and check attributes. It will be older one instead of English (which is default).