ComboPopup () { if (comboBox.getClientProperty(DarculaJBPopupComboPopup.CLIENT_PROP) != null) { return new DarculaJBPopupComboPopup<>(comboBox) { @Override public void configureList(@NotNull JList<Object> list) { super.configureList(list); list.setSelectionBackground(JBColor.lazy(() -> ColorUtil.withAlpha(UIManager.getColor("ComboBox.selectionBackground"), 0.75))); } }; } return new CustomComboPopup(comboBox) { @Override protected void configureList() { super.configureList(); list.setSelectionBackground(JBColor.lazy(() -> ColorUtil.withAlpha(UIManager.getColor("ComboBox.selectionBackground"), 0.75))); } }; }