in src/main/java/com/intellij/util/ui/UIUtilities.java [1449:1476]
public static Component compositeRequestFocus(Component component) {
if (component instanceof Container) {
Container container = (Container)component;
if (container.isFocusCycleRoot()) {
FocusTraversalPolicy policy = container.getFocusTraversalPolicy();
Component comp = policy.getDefaultComponent(container);
if (comp!=null) {
comp.requestFocus();
return comp;
}
}
Container rootAncestor = container.getFocusCycleRootAncestor();
if (rootAncestor!=null) {
FocusTraversalPolicy policy = rootAncestor.getFocusTraversalPolicy();
Component comp = policy.getComponentAfter(rootAncestor, container);
if (comp!=null && SwingUtilities.isDescendingFrom(comp, container)) {
comp.requestFocus();
return comp;
}
}
}
if (component.isFocusable()) {
component.requestFocus();
return component;
}
return null;
}