Overlay.addOverlay
void addOverlay(gtk.widget.Widget widget)Adds widget to overlay.
The widget will be stacked on top of the main widget added with [gtk.overlay.Overlay.setChild].
The position at which widget is placed is determined from its [gtk.widget.Widget.halign] and [gtk.widget.Widget.valign] properties.
Parameters
widget | a [gtk.widget.Widget] to be added to the container |