Can not reproduce it on my 7.23.5-project running locally. What happens if you start a new 7.23.5 or 7.23.6 project? Do you get the same dot? If not, try overwriting the theme-directory the Atlas_UI_Resources with the new ones.
There is some wierd theme-errors going on in version beta-3. Might be related if Mendix is also modifing related code in 7.23.5/6 although I am not aware of any of these.