Embed gtk window?

[zhum]

Hello! I want to port my ruby-based XScreenSaver mod to crystal. The main question is - how to embed gtk3 window into XScreenSaver window. In gtk2 it could be done by this trick:

self.window=Gdk::Window.foreign_new(xid)

where xid is passed in XSCREENSAVER_WINDOW environment variable.
Is possible to make something like this in gtk3 crystal implementation?