code: private void updateTextured() {
          // Need the content pane to not be opaque.
          paintTextured = (root.getClientProperty(UNIFIED_TOOLBAR_LOOK) == Boolean.TRUE);
  
          if (paintTextured && PlatformUtils.isMac()) {
              if (root.isValid()) {
                  throw new IllegalArgumentException("This method only works if the given JRootPane has not yet been realized.");
              }
  
              root.putClientProperty("apple.awt.brushMetalLook", Boolean.TRUE);
  
              // Need the content pane to not be opaque.
              LookAndFeel.installProperty((JComponent) root.getContentPane(), "opaque", Boolean.FALSE);
          } else {
              root.putClientProperty("apple.awt.brushMetalLook", null);
              // FIXME Restore original content pane opacity.
          }
      }
docs: Set the textured properties.