if (response.getDrawingCanvas() != null) { if (control.getDrawingCanvas() == null) control.setDrawingCanvas(response.getDrawingCanvas());
control.setDrawingCanvas(response.getDrawingCanvas());
    private void handleDisplayROI(DisplayROI response)    {        if (response.getDrawingCanvas() != null) { //close window            if (control.getDrawingCanvas() == null)                control.setDrawingCanvas(response.getDrawingCanvas());            if (presentation == null) buildPresentation();            presentation.deIconify();        } else removePresentation();    }