/**
 * Split the editor area if there is at least two editors in it.
 */
private void splitEditorArea() {
	IWorkbenchPage workbenchPage = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
	IWorkbenchPart part = workbenchPage.getActivePart();
	PartPane partPane = ((PartSite) part.getSite()).getPane();
	LayoutPart layoutPart = partPane.getPart();
 
	IEditorReference[] editorReferences = workbenchPage.getEditorReferences();
	// Do it only if we have more that one editor
	if (editorReferences.length > 1) {
		// Get PartPane that correspond to the active editor
		PartPane currentEditorPartPane = ((PartSite) workbenchPage.getActiveEditor().getSite()).getPane();
		EditorSashContainer editorSashContainer = null;
		ILayoutContainer rootLayoutContainer = layoutPart.getContainer();
		if (rootLayoutContainer instanceof LayoutPart) {
			ILayoutContainer editorSashLayoutContainer = ((LayoutPart) rootLayoutContainer).getContainer();
			if (editorSashLayoutContainer instanceof EditorSashContainer) {
				editorSashContainer = ((EditorSashContainer) editorSashLayoutContainer);
			}
		}
		/*
		 * Create a new part stack (i.e. a workbook) to home the
		 * currentEditorPartPane which hold the active editor
		 */
		PartStack newPart = createStack(editorSashContainer);
		editorSashContainer.stack(currentEditorPartPane, newPart);
		if (rootLayoutContainer instanceof LayoutPart) {
			ILayoutContainer cont = ((LayoutPart) rootLayoutContainer).getContainer();
			if (cont instanceof PartSashContainer) {
				// "Split" the editor area by adding the new part
				((PartSashContainer) cont).add(newPart);
			}
		}
	}
}
 
/**
 * A method to create a part stack container (a new workbook)
 * 
 * @param editorSashContainer the <code>EditorSashContainer</code> to set for the returned <code>PartStack</code>
 * @return a new part stack container
 */
private PartStack createStack(EditorSashContainer editorSashContainer) {
	WorkbenchPage workbenchPage = (WorkbenchPage) PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
	EditorStack newWorkbook = EditorStack.newEditorWorkbook(editorSashContainer, workbenchPage);
	return newWorkbook;
}