If this function is called on a window with setting of true, before it is realized or showed, it will have a "frame" window around widget->window, accessible in window->frame. Or it access the "frame" window exterior to widget->window.
true if a frame has been added to the window via Window.HasFrame.
Using the event WIndow.FrameEvent you can receive all events targeted at the frame. This method is used by the linux-fb port to implement managed windows, but it could concievably be used by X-programs that want to do their own window decorations.
Note: This is a special-purpose method for the framebuffer port, this causes GTK# to draw its own window border. For most applications you want Window.Decorated instead, which tells the window manager whether to draw the window border.