Fix some small data laboratory issues (workspace related)

modules/DesktopDataLaboratory/src/main/java/org/gephi/desktop/datalab/DataTableTopComponent.java

@@ -250,6 +250,9 @@ public class DataTableTopComponent extends TopComponent implements AWTEventListe
         Lookup.getDefault().lookup(DataTablesController.class).setDataTablesEventListener(DataTableTopComponent.this);
 
         dataTablesModel = workspace.getLookup().lookup(DataTablesModel.class);
+        if (dataTablesModel == null) {
+            workspace.add(dataTablesModel = new DataTablesModel(workspace));
+        }
         nodeAvailableColumnsModel = dataTablesModel.getNodeAvailableColumnsModel();
         edgeAvailableColumnsModel = dataTablesModel.getEdgeAvailableColumnsModel();
         hideTable();

modules/VisualizationImpl/src/main/java/org/gephi/visualization/apiimpl/contextmenuitems/CopyOrMoveToWorkspaceSubItem.java

@@ -43,6 +43,7 @@ package org.gephi.visualization.apiimpl.contextmenuitems;
 
 import java.util.Arrays;
 import javax.swing.Icon;
+import org.gephi.datalab.spi.nodes.NodesManipulator;
 import org.gephi.desktop.project.api.ProjectControllerUI;
 import org.gephi.graph.api.Graph;
 import org.gephi.graph.api.GraphController;
@@ -54,7 +55,7 @@ import org.gephi.project.api.WorkspaceInformation;
 import org.openide.util.Lookup;
 import org.openide.util.NbBundle;
 
-public class CopyOrMoveToWorkspaceSubItem extends BasicItem {
+public class CopyOrMoveToWorkspaceSubItem extends BasicItem implements NodesManipulator {
 
     private final Workspace workspace;
     private final boolean canExecute;