undoAction= new UndoActionHandler(getSite(), undoContext);
undoAction.setActionDefinitionId(IWorkbenchCommandConstants.EDIT_UNDO);
redoAction= new RedoActionHandler(getSite(), undoContext);
redoAction.setActionDefinitionId(IWorkbenchCommandConstants.EDIT_REDO);
copyAction = new CopyAction(this);
copyAction.setActionDefinitionId(IWorkbenchCommandConstants.EDIT_COPY);
addPartPropertyListener((IPropertyChangeListener) copyAction);
copyAction.setEnabled(false);
pasteAction = new PasteAction(this);
pasteAction.setActionDefinitionId(IWorkbenchCommandConstants.EDIT_PASTE);