Is there an MDI form for GTK 3 or 2 in Ruby?

Is there a class that defines an MDI form in Ruby GTK 2 or 3, similar to that found in other languages like Delphi, C #, VB etc.?

Note: MDI is that form for desktop applications that one window opens inside another, that is, it is in the scope of the main window, not coming out of it.