public EditorPanel openNewSequenceEditor(UmlModel umlModel) {
GeneralDiagram diagram = new SequenceDiagram(umlModel);
diagram.setLabelText(ApplicationResources.getInstance().getString(
"stdcaption.sequencediagram") + " " + (sequenceCounter++));
umlModel.addDiagram(diagram);
return createEditorPanel(new SequenceDiagramEditor(
shell.getShellComponent(), diagram),
new SequenceEditorToolbarManager());
}