zeusgo
picutre 1 . gray background sidebar is plugin insert.
here is my code.
const barContainer = NSView.alloc().initWithFrame(NSMakeRect(0, 0, 50, 0));
const viewController = NSViewController.alloc().init();
viewController.view = barContainer;
const splitViewItem = NSSplitViewItem.splitViewItemWithViewController(viewController);
document.splitViewController().insertSplitViewItem_atIndex(splitViewItem, 2);
