Moves @child to a new @index in the list of @overlay children.
The list contains overlays in the order that these were
added to @overlay.
A widget’s index in the @overlay children list determines which order
the children are drawn if they overlap. The first child is drawn at
the bottom. It also affects the default focus chain order.
Moves @child to a new @index in the list of @overlay children. The list contains overlays in the order that these were added to @overlay.
A widget’s index in the @overlay children list determines which order the children are drawn if they overlap. The first child is drawn at the bottom. It also affects the default focus chain order.