So I added it, but I could not implement "add(button)" ; I imported a lot of nebula...
So I send the code snippet concerning this problem. Where is "add(button)" defined ???
import java.io.File;
import java.io.IOException;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.text.SimpleDateFormat;
import java.util.*;
 
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileFilter;
import javax.swing.filechooser.FileNameExtensionFilter;
 
import org.eclipse.core.*;
import org.eclipse.core.commands.*;
import org.eclipse.equinox.*;
import org.eclipse.osgi.*;
import org.eclipse.draw2d.*;
import org.eclipse.nebula.visualization.xygraph.*;
import org.eclipse.swt.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.nebula.visualization.xygraph.dataprovider.CircularBufferDataProvider;
import org.eclipse.nebula.visualization.xygraph.figures.*;
import org.eclipse.nebula.visualization.xygraph.figures.Trace.PointStyle;
import org.eclipse.nebula.visualization.xygraph.figures.Trace.TraceType;
import org.eclipse.nebula.visualization.xygraph.util.XYGraphMediaFactory;
import org.eclipse.nebula.visualization.xygraph.figures.ToolbarArmedXYGraph;
 
import org.eclipse.nebula.visualization.xygraph.figures.XYGraphToolbar;
 
import org.eclipse.draw2d.Button;
//import org.eclipse.draw2d.ButtonGroup;
import org.eclipse.draw2d.Label;
import org.eclipse.draw2d.Clickable;
 
 
 
public class PlotKomp  // wird von Fileread.java aufgerufen
{   
       public void addButton(Clickable button)
       {
          button.setPreferredSize(25, 25);
          add(button);                                                                DOES NOT WORK
       }
 
      
       public void drawGraph(String pfad)
       {
Display display = Display.getDefault();
          Shell shell = new Shell(display);
         
       
             shell.setSize(600, 450);
             shell.open()
             shell.setLocation(100, 100)
             LightweightSystem lwssio2 = new LightweightSystem(shell);
             XYGraph xysio2graph = new XYGraph();
            
            
             ToolbarArmedXYGraph toolbarArmedXYGraph = new ToolbarArmedXYGraph(xysio2graph);  //23.11
          
             xysio2graph.setTitle("SiO2");
              //23.11            lwssio2.setContents(xysio2graph);
             lwssio2.setContents(toolbarArmedXYGraph);
            
            
             // Configure XYGraph
             xysio2graph.primaryXAxis.setShowMajorGrid(true);
             xysio2graph.primaryYAxis.setShowMajorGrid(true);
           
             // Bezeichnung der Achsen
             xysio2graph.primaryXAxis.setTitle("XRD-Value [%]");
             xysio2graph.primaryYAxis.setTitle("XRF-Value [%]");
            
             // Create a trace data provider, which will provide the data to the trace XRD and XRF        
             CircularBufferDataProvider tdpsio2 = new CircularBufferDataProvider(false);
             tdpsio2.setBufferSize(200);  
    
             tdpsio2.setCurrentXDataArray(arrsio2xrdend);
             tdpsio2.setCurrentYDataArray(arrsio2rfaend);
          // Create a trace data provider for the line
            
             Trace tracesio2 = new Trace("SiO2-XY Plot", xysio2graph.primaryXAxis, xysio2graph.primaryYAxis, tdpsio2);
             tracesio2.setTraceType(TraceType.POINT);
             tracesio2.setPointStyle(PointStyle.FILLED_DIAMOND);
             tracesio2.setPointSize(10);
             tracesio2.setAreaAlpha(250);
             tracesio2.setTraceColor(XYGraphMediaFactory.getInstance().getColor(XYGraphMediaFactory.COLOR_BLUE));
           
             xysio2graph.addTrace(tracesio2);
 
             CircularBufferDataProvider tdpsio2line = new CircularBufferDataProvider(false);
             tdpsio2line.setBufferSize(200);           
             tdpsio2line.setCurrentXDataArray(new double[]{0.0, 50.0, 100.0});
             tdpsio2line.setCurrentYDataArray(new double[]{0.0, 50.0, 100.0});
            
             Trace tracesio2line = new Trace("SiO2-XY Plot", xysio2graph.primaryXAxis, xysio2graph.primaryYAxis, tdpsio2line);
            
             tracesio2line.setTraceType(TraceType.SOLID_LINE);
             tracesio2line.setLineWidth(2);
             tracesio2line.setTraceColor(XYGraphMediaFactory.getInstance().getColor(XYGraphMediaFactory.COLOR_BLACK));
            
             xysio2graph.addTrace(tracesio2line);
       
 
Button     snapShotButton = new Button(XYGraphMediaFactory.getInstance().getImage("images/camera.png"));  //
        snapShotButton.setToolTip(new Label("Save Snapshot to PNG file"));
      //  addButton...