https://docs.oracle.com/javase/jp/18/docs/api/java.desktop/javax/swing/plaf/metal/MetalToolBarUI.MetalDockingListener.html
MetalToolBarUI.MetalDockingListener (Java SE 18 & JDK 18)
declaration: module: java.desktop, package: javax.swing.plaf.metal, class: MetalToolBarUI, class: MetalDockingListener
java sejdk