private void checkSelection(EntityManager entityManager) {
        for (int x = (int) selectionStart.x; x <= (int) selectionEnd.x; x++) {
            for (int y = (int) selectionStart.y; y <= (int) selectionEnd.y; y++) {
                Node n = World.nodeAt(x, y);
                if (n != null) {
                    Entity entity = n.standing;
                    if (entity instanceof SelectableUnit) {
                        if (!selectionManager.currentSelectionContains(entity)) {
                            selectionManager.addCurrentSelection(entity);
                            if (entity instanceof Unit) {
                                ((SelectableUnit) entity).setSelected(true);
                            }
                        }
                    }
                }
                if (selectionStart.x == selectionEnd.x && selectionStart.y == selectionEnd.y) {
                    System.out.println("Unit at this spot is " + World.nodeAt(selectionEnd.x, selectionEnd.y).standing);
                }
            }
        }
        setAbilityButtons(selectionManager.getCurrentSelection());
    }