final IMultiDiagramEditor editor = EditorUtils.getMultiDiagramEditor(); 
Display.getCurrent().asyncExec(new Runnable() {
	public void run() {
		IWorkbench wb = PlatformUI.getWorkbench();
		IWorkbenchPage page = wb.getActiveWorkbenchWindow().getActivePage();
		IEditorInput input = editor.getEditorInput();
		page.closeEditor(editor, false);
		try {
			IEditorDescriptor desc = wb.getEditorRegistry().getDefaultEditor(input.getName());
			page.openEditor(input, desc.getId(), false);
		} catch (PartInitException e) {
			e.printStackTrace();
		}
	}
});