layer
Places the child on the depth layer. Higher values paint above lower ones: name a well-known JLayeredPane layer (JLayeredPane.DEFAULT_LAYER, PALETTE_LAYER, MODAL_LAYER, POPUP_LAYER, DRAG_LAYER) or any other integer depth.
A depth is the layout constraint the pane places the child under, so the last placement a chain declares wins, and a chain declaring none leaves the child on JLayeredPane.DEFAULT_LAYER. Within one layer the children stack in the order the composition declares them, the first of them on top. Declaring a different depth moves the child to position 0 - the topmost position within a layer - of the layer it names, keeping what it remembers and the component it is realized as.
The child positions itself within the pane through SwingModifier.bounds(...), since a layered pane lays no child out.
Return
this chain with the depth declared on it.
Parameters
the depth the child is placed at