GtkOverlay is a container which contains a single main child, on top
of which it can place “overlay” widgets. The position of each overlay
widget is determined by its #GtkWidget:halign and #GtkWidget:valign
properties. E.g. a widget with both alignments set to gtk.types.Align.Start
will be placed at the top left corner of the GtkOverlay container,
whereas an overlay with halign set to gtk.types.Align.Center and valign set
to gtk.types.Align.End will be placed a the bottom edge of the GtkOverlay,
horizontally centered. The position can be adjusted by setting the margin
properties of the child to non-zero values.
More complicated placement of overlays is possible by connecting
to the #GtkOverlay::get-child-position signal.
An overlay’s minimum and natural sizes are those of its main child. The sizes
of overlay children are not considered when measuring these preferred sizes.
GtkOverlay as GtkBuildable
The GtkOverlay implementation of the GtkBuildable interface
supports placing a child as an overlay by specifying “overlay” as
the “type” attribute of a <child> element.
CSS nodes
GtkOverlay has a single CSS node with the name “overlay”. Overlay children
whose alignments cause them to be positioned at an edge get the style classes
“.left”, “.right”, “.top”, and/or “.bottom” according to their position.
GtkOverlay is a container which contains a single main child, on top of which it can place “overlay” widgets. The position of each overlay widget is determined by its #GtkWidget:halign and #GtkWidget:valign properties. E.g. a widget with both alignments set to gtk.types.Align.Start will be placed at the top left corner of the GtkOverlay container, whereas an overlay with halign set to gtk.types.Align.Center and valign set to gtk.types.Align.End will be placed a the bottom edge of the GtkOverlay, horizontally centered. The position can be adjusted by setting the margin properties of the child to non-zero values.
More complicated placement of overlays is possible by connecting to the #GtkOverlay::get-child-position signal.
An overlay’s minimum and natural sizes are those of its main child. The sizes of overlay children are not considered when measuring these preferred sizes.
GtkOverlay as GtkBuildable
The GtkOverlay implementation of the GtkBuildable interface supports placing a child as an overlay by specifying “overlay” as the “type” attribute of a <child> element.
CSS nodes
GtkOverlay has a single CSS node with the name “overlay”. Overlay children whose alignments cause them to be positioned at an edge get the style classes “.left”, “.right”, “.top”, and/or “.bottom” according to their position.