EDIT

import org.eclipse.jface.window.Window;

    private EventList<RowWrapper> descriptions;

        descriptions = GlazedLists.eventList(getDescriptions(workingSet));

        /**

         * Add description button

         */

        Button btnAddDescription = new Button(parent, SWT.PUSH);

        btnAddDescription.setImage(ImageResources.getImage(ImageResources.ADD_ICON));

        btnAddDescription.addSelectionListener(new SelectionAdapter() {

            @Override

            public void widgetSelected(SelectionEvent e) {

                DescriptionSelectionDialog dialog = new DescriptionSelectionDialog(natTable.getShell(), workingSet);

                if(dialog.open()==Window.OK){

                    Collection<DescriptionBase> selectedDescriptions = dialog.getDescriptions();

                    boolean hasAdded = false;

                    for (DescriptionBase description : selectedDescriptions) {

                        if(!workingSet.getDescriptions().contains(description)){

                            CharacterMatrix.this.descriptions.add(new RowWrapper((SpecimenDescription) description));

                            workingSet.addDescription(description);

                            hasAdded = true;

                        }

                    }

                    if(hasAdded){

                        setDirty();

                    }

                }

            }

        });

/**

* Copyright (C) 2018 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.taxeditor.editor.workingSet.matrix;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Set;

import org.eclipse.jface.dialogs.Dialog;

import org.eclipse.jface.viewers.ArrayContentProvider;

import org.eclipse.jface.viewers.IStructuredSelection;

import org.eclipse.jface.viewers.LabelProvider;

import org.eclipse.jface.viewers.TableViewer;

import org.eclipse.swt.graphics.Image;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Control;

import org.eclipse.swt.widgets.Shell;

import eu.etaxonomy.cdm.api.service.IOccurrenceService;

import eu.etaxonomy.cdm.hibernate.HibernateProxyHelper;

import eu.etaxonomy.cdm.model.description.DescriptionBase;

import eu.etaxonomy.cdm.model.description.SpecimenDescription;

import eu.etaxonomy.cdm.model.description.WorkingSet;

import eu.etaxonomy.cdm.model.occurrence.SpecimenOrObservationBase;

import eu.etaxonomy.cdm.model.taxon.ITaxonTreeNode;

import eu.etaxonomy.cdm.model.taxon.Taxon;

import eu.etaxonomy.cdm.model.taxon.TaxonNode;

import eu.etaxonomy.taxeditor.model.ImageResources;

import eu.etaxonomy.taxeditor.store.CdmStore;

/**

 * @author pplitzner

 * @since Jan 3, 2018

 *

 */

public class DescriptionSelectionDialog extends Dialog {

    private TableViewer list;

    private WorkingSet workingSet;

    Collection<DescriptionBase> selectedDescriptions = new ArrayList<>();

    protected DescriptionSelectionDialog(Shell parentShell, WorkingSet workingSet) {

        super(parentShell);

        this.workingSet = workingSet;

    }

    @Override

    protected Control createDialogArea(Composite parent) {

        Composite composite = (Composite) super.createDialogArea(parent);

        list = new TableViewer(composite);

        list.setContentProvider(new ArrayContentProvider());

        list.setLabelProvider(new DescriptionLabelProvider());

        //gather descriptions

        Collection<DescriptionBase> descriptions = new ArrayList<>();

        Set<TaxonNode> taxonNodes = workingSet.getTaxonSubtreeFilter();

        for (ITaxonTreeNode taxonTreeNode : taxonNodes) {

            if(taxonTreeNode instanceof TaxonNode){

                TaxonNode taxonNode = (TaxonNode)taxonTreeNode;

                workingSet.addTaxonSubtree(taxonNode);

                if(taxonNode.getTaxon()!=null){

                    Taxon taxon = HibernateProxyHelper.deproxy(taxonNode.getTaxon(), Taxon.class);

                    Collection<SpecimenOrObservationBase> specimens = CdmStore.getService(IOccurrenceService.class).listByAssociatedTaxon(SpecimenOrObservationBase.class, null, taxon, null, null, null, null, null);

                    for (SpecimenOrObservationBase specimen : specimens) {

                        Set<SpecimenDescription> specimenDescriptions = specimen.getSpecimenDescriptions();

                        for (SpecimenDescription specimenDescription : specimenDescriptions) {

                            descriptions.add(specimenDescription);

                        }

                    }

                }

            }

        }

        list.setInput(descriptions);

        return composite;

    }

    /**

     * {@inheritDoc}

     */

    @Override

    protected void okPressed() {

        selectedDescriptions = ((IStructuredSelection)list.getSelection()).toList();

        super.okPressed();

    }

    public Collection<DescriptionBase> getDescriptions(){

        return selectedDescriptions;

    }

    private class DescriptionLabelProvider extends LabelProvider{

        /**

         * {@inheritDoc}

         */

        @Override

        public Image getImage(Object element) {

            if(workingSet.getDescriptions().contains(element)){

                return ImageResources.getImage(ImageResources.SYNCED);

            }

            return null;

        }

    }

}