public void set_attached_to (Widget? attach_widget)
Marks this as attached to
This creates a logical binding between the window and the widget it belongs to, which is used by GTK+ to propagate information such as styling
or accessibility to this as if it was a children of
Note that this function should not be confused with set_transient_for, which specifies a window manager relation between two toplevels instead.
Passing null for
attach_widget detaches the window.
a Widget, or null