"Use Class Defaults" not working properly

[V K]

I found message in this list where Jürgen wrote, that "use class defaults" button "should apply to the following settings: 
* oneside/twoside 
* columns 
* page style 
* toc level 
And resets to what is defined as default (if any) in the layout file."

New Beamer class document (with "use class defaults" applied) compiles a pdf with margins from the article class and even A4 paper format. And there is no opportunity to change margins or paper format, because they are greyed out. User must revert to the article class, apply it (with warnings), change to defaults, apply them (with warnings) and revert back to Beamer. Nonetheless pdf after compiling has margins from the article class despite "Default margins" box were ticked – user must delete numbers from margin boxes – only then margins from article class disappear. So "Default margins" box isn't working in this case.
I couldn't find what is wrong with the margins quite a long time until checked code preview pane and saw preamble with margins defined. 
I think it is a bug and "use class defaults" should reset at least margins and paper format (and maybe some other parameters, as text layout) to defaults.

Best regards,

Valdemaras