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

Question

There is 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 a window is opened inside another, that is, it is in the scope of the main window, not leaving outside it.