Basic implementation of BrowseFolderDialog and Win32 Implementation.

src/Perspex.Controls/Platform/ISystemDialogImpl.cs

@@ -18,5 +18,7 @@ namespace Perspex.Controls.Platform
         /// <param name="parent">The parent window.</param>
         /// <returns>A task returning the selected filenames.</returns>
         Task<string[]> ShowFileDialogAsync(FileDialog dialog, IWindowImpl parent);
+
+        Task<string> ShowFolderDialogAsync(OpenFolderDialog dialog, IWindowImpl parent);   
     }
 }

src/Perspex.Controls/SystemDialog.cs

@@ -12,10 +12,9 @@ namespace Perspex.Controls
         public string InitialDirectory { get; set; }
     }
 
-
     public class SaveFileDialog : FileDialog
     {
-        public string DefaultExtension { get; set; }
+        public string DefaultExtension { get; set; }        
 
         public async Task<string> ShowAsync(Window window = null)
             =>
@@ -31,6 +30,12 @@ namespace Perspex.Controls
             => PerspexLocator.Current.GetService<ISystemDialogImpl>().ShowFileDialogAsync(this, window?.PlatformImpl);
     }
 
+    public class OpenFolderDialog : SystemDialog
+    {
+        public Task<string> ShowAsync(Window window = null)
+               => PerspexLocator.Current.GetService<ISystemDialogImpl>().ShowFolderDialogAsync(this, window?.PlatformImpl);
+    }
+
     public abstract class SystemDialog
     {
         public string Title { get; set; }

src/Windows/Perspex.Win32/Perspex.Win32.csproj

@@ -38,6 +38,10 @@
     <NoWarn>CS1591</NoWarn>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="Ookii.Dialogs.Wpf, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0c15020868fd6249, processorArchitecture=MSIL">
+      <HintPath>..\..\..\packages\Ookii.Dialogs.1.0\lib\net35\Ookii.Dialogs.Wpf.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
     <Reference Include="System.Drawing" />

src/Windows/Perspex.Win32/SystemDialogImpl.cs

@@ -10,6 +10,7 @@ using Perspex.Controls;
 using Perspex.Controls.Platform;
 using Perspex.Platform;
 using Perspex.Win32.Interop;
+using Ookii.Dialogs.Wpf;
 
 namespace Perspex.Win32
 {
@@ -128,5 +129,17 @@ namespace Perspex.Win32
                 return files.Select(f => Path.Combine(dir, f)).ToArray();
             });
         }
+
+        public Task<string> ShowFolderDialogAsync(OpenFolderDialog dialog, IWindowImpl parent)
+        {
+            VistaFolderBrowserDialog fbd = new VistaFolderBrowserDialog();
+
+            return Task.Factory.StartNew(() =>
+            {
+                fbd.ShowDialog();
+
+                return fbd.SelectedPath;
+            });
+        }
     }
 }

src/Windows/Perspex.Win32/packages.config

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
+  <package id="Ookii.Dialogs" version="1.0" targetFramework="net45" />
   <package id="Rx-Core" version="2.2.5" targetFramework="net45" />
   <package id="Rx-Interfaces" version="2.2.5" targetFramework="net45" />
   <package id="Rx-Linq" version="2.2.5" targetFramework="net45" />