if (index == -1) return;
    public void copyPlaneArea(PlaneArea pa, int newZ, int newT)    {        int index = presentation.getToolBar().getSelectedIndex();        abstraction.copyPlaneArea(pa, index, newZ, newT);        if (newT == getCurrentT() && newZ == getCurrentZ()) {            PlaneArea p = abstraction.getPlaneArea(newZ, newT, index);            if (p != null) {                p.scale(abstraction.getMagFactor());                drawingCanvas.setPlaneArea(p, index);            }        }    }