Root Pane Containers - The Definitive Guide to Java Swing - page 230

tooltip text appear in front of any other Swing components. In the back is the JLayeredPane ,
which contains an optional JMenuBar on top and a content pane ( Container ) below it in another
layer. It is within the content pane that you would normally place components in the
JRootPane . Figure 8-1 should help you visualize how the RootLayout lays out the components.
*-ENU"AR
#ONTENT0ANE#ONTAINER
'LASS0ANE#OMPONENT
Figure 8-1. JRootPane containment diagram
■ Note A JLayeredPane is just another Swing container (it's described later in this chapter). It can contain
any components and has a special layering characteristic. The default JLayeredPane used within the
JRootPane pane contains only a JMenuBar and a Container as its content pane. The content pane has
its own layout manager, which is BorderLayout by default.
Creating a JRootPane
Although the JRootPane has a public no-argument constructor, a JRootPane isn't something
you would normally create yourself. Instead, a class that implements the RootPaneContainer
interface creates the JRootPane . Then, you can get the root pane from that component, through
the RootPaneContainer interface, described shortly.
JRootPane Properties
As Table 8-1 shows, there are 11 properties of JRootPane . In most cases, when you get or set one
of these properties for a top-level container, like JFrame , the container simply passes along the
request to its JRootPane .
The glass pane for a JRootPane must not be opaque. Because the glass pane takes up the
entire area in front of the JLayeredPane , an opaque glass pane would render the menu bar and
content pane invisible. And, because the glass pane and content pane share the same bounds,
the optimizedDrawingEnabled property returns the visibility of the glass pane as its setting.