 
 // MARK: - NSOutlineViewDataSource
 extension FileOutlineView {
+
+  fileprivate func prepare(_ children: [FileBrowserItem]) -> [FileBrowserItem] {
+    return children.filter { !$0.fileItem.isHidden }.sorted()
+  }
 
   func outlineView(_: NSOutlineView, numberOfChildrenOfItem item: Any?) -> Int {
     if item == nil {

    let fileItem = fileBrowserItem.fileItem
    if fileItem.isDir {
      let fileItemChildren = self.fileItemService.fileItemWithChildren(for: fileItem.url)?.children ?? []
      fileBrowserItem.children = fileItemChildren.map(FileBrowserItem.init)
      return fileBrowserItem.children.filter { !$0.fileItem.isHidden }.count
    }

    return 0


    if item == nil {
      self.adjustColumnWidth(for: self.root.children, outlineViewLevel: level)
      return self.prepare(self.root.children)[index]
    }

    guard let fileBrowserItem = item as? FileBrowserItem else {
