Make icons work; Define a ItemType to correctly define the navigation item type (file, folder, volume, etc).

src/Avalonia.Dialogs/ManagedFileChooser.xaml

@@ -27,6 +27,12 @@
                 <GeometryDrawing Brush="#FF9B4E96" Geometry="F1M12,13L4,13 4,3 9,3 9,6 12,6z M9.641,2L3.964,2C3.964,2,3,2,3,3L3,13C3,14,3.964,14,3.964,14L11.965,14C12.965,14,13,13,13,13L13,5z" />
                 <GeometryDrawing Brush="#FFF0EFF1" Geometry="F1M4,3L9,3 9,6 12,6 12,13 4,13z" />
             </DrawingGroup>
+            <DrawingGroup x:Key="Icon_Volume">
+                <GeometryDrawing Brush="#00FFFFFF" Geometry="F1M16,16L0,16 0,0 16,0z" />
+                <GeometryDrawing Brush="#FFF6F6F6" Geometry="F1M0,12L0,6.5C0,5.122,1.122,4,2.5,4L13.5,4C14.879,4,16,5.122,16,6.5L16,12z" />
+                <GeometryDrawing Brush="#FFEFEFF0" Geometry="F1M13,8L12,8 12,7 13,7z M11,8L10,8 10,7 11,7z M13.5,6L2.5,6C2.224,6,2,6.224,2,6.5L2,10 14,10 14,6.5C14,6.224,13.775,6,13.5,6" />
+                <GeometryDrawing Brush="#FF424242" Geometry="F1M13,7L12,7 12,8 13,8z M11,7L10,7 10,8 11,8z M2,10L14,10 14,6.5C14,6.224,13.775,6,13.5,6L2.5,6C2.224,6,2,6.224,2,6.5z M15,11L1,11 1,6.5C1,5.673,1.673,5,2.5,5L13.5,5C14.327,5,15,5.673,15,6.5z" />
+            </DrawingGroup>
         </dialogs:ResourceSelectorConverter>
     </UserControl.Resources>
     <DockPanel>

src/Avalonia.Dialogs/ManagedFileChooser.xaml.cs

@@ -37,13 +37,13 @@ namespace Avalonia.Dialogs
             var isQuickLink = _quickLinksRoot.IsLogicalParentOf(e.Source as Control);
             if (e.ClickCount == 2 || isQuickLink)
             {
-                if (model.IsDirectory)
+                if (model.ItemType == ManagedFileChooserItemType.File)
                 {
-                    Model?.Navigate(model.Path);
+                    Model?.SelectSingleFile(model);
                 }
                 else
                 {
-                    Model?.SelectSingleFile(model);
+                    Model?.Navigate(model.Path);
                 }
 
                 e.Handled = true;

src/Avalonia.Dialogs/ManagedFileChooserItemType.cs

@@ -0,0 +1,9 @@
+namespace Avalonia.Dialogs
+{
+    public enum ManagedFileChooserItemType
+    {
+        File,
+        Folder,
+        Volume
+    }
+}

src/Avalonia.Dialogs/ManagedFileChooserItemViewModel.cs

@@ -6,10 +6,10 @@ namespace Avalonia.Dialogs
     {
         private string _displayName;
         private string _path;
-        private bool _isDirectory;
-        private DateTime _modified;
+         private DateTime _modified;
         private string _type;
         private long _size;
+        private ManagedFileChooserItemType _itemType;
 
         public string DisplayName
         {
@@ -41,27 +41,35 @@ namespace Avalonia.Dialogs
             set => this.RaiseAndSetIfChanged(ref _size, value);
         }
 
-        public string IconKey => IsDirectory ? "Icon_Folder" : "Icon_File";
+        public ManagedFileChooserItemType ItemType
+        {
+            get => _itemType;
+            set => this.RaiseAndSetIfChanged(ref _itemType, value);
+        }
 
-        public bool IsDirectory
+        public string IconKey
         {
-            get => _isDirectory;
-            set
+            get
             {
-                if (this.RaiseAndSetIfChanged(ref _isDirectory, value))
+                switch (ItemType)
                 {
-                    this.RaisePropertyChanged(nameof(IconKey));
+                    case ManagedFileChooserItemType.Folder:
+                        return "Icon_Folder";
+                    case ManagedFileChooserItemType.Volume:
+                        return "Icon_Volume";
+                    default:
+                        return "Icon_File";
                 }
             }
         }
-
+ 
         public ManagedFileChooserItemViewModel()
         {
         }
 
         public ManagedFileChooserItemViewModel(ManagedFileChooserNavigationItem item)
         {
-            IsDirectory = true;
+            ItemType = item.ItemType;
             Path = item.Path;
             DisplayName = item.DisplayName;
         }

src/Avalonia.Dialogs/ManagedFileChooserNavigationItem.cs

@@ -4,5 +4,6 @@
     {
         public string DisplayName { get; set; }
         public string Path { get; set; }
+        public ManagedFileChooserItemType ItemType { get; set; }
     }
 }

src/Avalonia.Dialogs/ManagedFileChooserSources.cs

@@ -43,6 +43,7 @@ namespace Avalonia.Dialogs
                 .Where(Directory.Exists)
                 .Select(d => new ManagedFileChooserNavigationItem
                 {
+                    ItemType = ManagedFileChooserItemType.Folder,
                     Path = d,
                     DisplayName = Path.GetFileName(d)
                 }).ToArray();
@@ -54,6 +55,7 @@ namespace Avalonia.Dialogs
             {
                 return DriveInfo.GetDrives().Select(d => new ManagedFileChooserNavigationItem
                 {
+                    ItemType = ManagedFileChooserItemType.Volume,
                     DisplayName = d.Name,
                     Path = d.RootDirectory.FullName
                 }).ToArray();
@@ -64,6 +66,7 @@ namespace Avalonia.Dialogs
 
                 return paths.Select(x => new ManagedFileChooserNavigationItem
                 {
+                    ItemType = ManagedFileChooserItemType.Volume,
                     DisplayName = Path.GetFileName(x),
                     Path = x
                 }).ToArray();
@@ -82,6 +85,7 @@ namespace Avalonia.Dialogs
                            {
                                return new ManagedFileChooserNavigationItem
                                {
+                                   ItemType = ManagedFileChooserItemType.Volume,
                                    DisplayName = "File System",
                                    Path = "/"
                                };
@@ -92,7 +96,7 @@ namespace Avalonia.Dialogs
 
                                return new ManagedFileChooserNavigationItem
                                {
-
+                                   ItemType = ManagedFileChooserItemType.Volume,
                                    DisplayName = dNameEmpty ? $"{ByteSizeHelper.ToString(x.DriveSizeBytes)} Volume"
                                                             : x.DriveLabel,
                                    Path = x.MountPath

src/Avalonia.Dialogs/ManagedFileChooserViewModel.cs

@@ -37,7 +37,6 @@ namespace Avalonia.Dialogs
         private bool _savingFile;
         private bool _scheduledSelectionValidation;
         private string _defaultExtension;
-        private CompositeDisposable _disposables;
 
         public string Location
         {
@@ -96,33 +95,28 @@ namespace Avalonia.Dialogs
             }
         }
 
-        private void RefreshQuickLinks()
+        private void RefreshQuickLinks(object _ = null)
         {
-            var quickSources = AvaloniaLocator.Current.GetService<ManagedFileChooserSources>()
-                           ?? new ManagedFileChooserSources();
+            var quickSources = AvaloniaLocator.Current
+                                              .GetService<ManagedFileChooserSources>()
+                                              ?? new ManagedFileChooserSources();
 
             QuickLinks.Clear();
-
             QuickLinks.AddRange(quickSources.GetAllItems().Select(i => new ManagedFileChooserItemViewModel(i)));
         }
 
         public ManagedFileChooserViewModel(FileSystemDialog dialog)
         {
-            _disposables = new CompositeDisposable();
-
-            var drivesInfoSrv = AvaloniaLocator.Current.GetService<IMountedDriveInfoProvider>()
-                             .MountedDrives;
+            var drivesInfoSrv = AvaloniaLocator.Current
+                                               .GetService<IMountedDriveInfoProvider>()
+                                               .MountedDrives;
 
             var sub1 = Observable.FromEventPattern(drivesInfoSrv, nameof(drivesInfoSrv.CollectionChanged))
-                                 .Subscribe((_) =>
-                                 {
-                                     Dispatcher.UIThread.InvokeAsync(RefreshQuickLinks);
-                                 });
-
-            _disposables.Add(sub1);
+                                 .ObserveOn(AvaloniaScheduler.Instance)
+                                 .Subscribe(RefreshQuickLinks);
 
-            CancelRequested += delegate { _disposables.Dispose(); };
-            CompleteRequested += delegate { _disposables.Dispose(); };
+            CompleteRequested += delegate { sub1?.Dispose(); };
+            CancelRequested += delegate { sub1?.Dispose(); };
 
             RefreshQuickLinks();
 
@@ -200,7 +194,7 @@ namespace Avalonia.Dialogs
                     }
                     else
                     {
-                        var invalidItems = SelectedItems.Where(i => i.IsDirectory).ToList();
+                        var invalidItems = SelectedItems.Where(i => i.ItemType == ManagedFileChooserItemType.Folder).ToList();
                         foreach (var item in invalidItems)
                         {
                             SelectedItems.Remove(item);
@@ -283,17 +277,18 @@ namespace Avalonia.Dialogs
                     {
                         DisplayName = info.Name,
                         Path = info.FullName,
-                        IsDirectory = info is DirectoryInfo,
                         Type = info is FileInfo ? info.Extension : "File Folder",
+                        ItemType = info is FileInfo ? ManagedFileChooserItemType.File
+                                                     : ManagedFileChooserItemType.Folder,
                         Size = info is FileInfo f ? f.Length : 0,
                         Modified = info.LastWriteTime
                     })
-                    .OrderByDescending(x => x.IsDirectory)
+                    .OrderByDescending(x => x.ItemType == ManagedFileChooserItemType.Folder)
                     .ThenBy(x => x.DisplayName, StringComparer.InvariantCultureIgnoreCase));
 
                     if (initialSelectionName != null)
                     {
-                        var sel = Items.FirstOrDefault(i => !i.IsDirectory && i.DisplayName == initialSelectionName);
+                        var sel = Items.FirstOrDefault(i => i.ItemType == ManagedFileChooserItemType.File && i.DisplayName == initialSelectionName);
 
                         if (sel != null)
                         {