Retrieves a gtk.layout_child.LayoutChild instance for the gtk.layout_manager.LayoutManager, creating one if necessary.
The child widget must be a child of the widget using manager.
The gtk.layout_child.LayoutChild instance is owned by the gtk.layout_manager.LayoutManager, and is guaranteed to exist as long as child is a child of the gtk.widget.Widget using the given gtk.layout_manager.LayoutManager.
a gtk.widget.Widget
a gtk.layout_child.LayoutChild
Retrieves a gtk.layout_child.LayoutChild instance for the gtk.layout_manager.LayoutManager, creating one if necessary.
The child widget must be a child of the widget using manager.
The gtk.layout_child.LayoutChild instance is owned by the gtk.layout_manager.LayoutManager, and is guaranteed to exist as long as child is a child of the gtk.widget.Widget using the given gtk.layout_manager.LayoutManager.