public boolean handleMouseWheelEvent(MouseWheelEvent e) { if ((e.getModifiers() & InputEvent.ALT_MASK) != 0) { logger.info("handleMouseWheelEvent entered."); MindMapNode rootNode = mMap.getRootNode(); if (e.getWheelRotation() > 0) { hookInstance.unfoldOneStage(rootNode); } else { // this is to avoid having selected nodes getting folded. controller.select(controller.getView().getRoot()); hookInstance.foldOneStage(rootNode); } return true; } return false; }