wabbajack/Wabbajack/UIUtils.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Threading;
using Microsoft.WindowsAPICodePack.Dialogs;
using Wabbajack.Common;

namespace Wabbajack
{
    public static class UIUtils
    {
        
        public static string ShowFolderSelectionDialog(string prompt)
        {
            if (Dispatcher.Thread != Thread.CurrentThread)
            {
                var task = new TaskCompletionSource<string>();
                Dispatcher.Invoke(() =>
                {
                    try
                    {
                        task.SetResult(ShowFolderSelectionDialog(prompt));
                    }
                    catch (Exception ex)
                    {
                        task.SetException(ex);
                    }
                });
                task.Task.Wait();
                if (task.Task.IsFaulted)
                    throw task.Task.Exception;
                return task.Task.Result;
            }


            var dlg = new CommonOpenFileDialog();
            dlg.Title = prompt;
            dlg.IsFolderPicker = true;
            dlg.InitialDirectory = Assembly.GetEntryAssembly().Location;

            dlg.AddToMostRecentlyUsedList = false;
            dlg.AllowNonFileSystemItems = false;
            dlg.DefaultDirectory = Assembly.GetEntryAssembly().Location;
            dlg.EnsureFileExists = true;
            dlg.EnsurePathExists = true;
            dlg.EnsureReadOnly = false;
            dlg.EnsureValidNames = true;
            dlg.Multiselect = false;
            dlg.ShowPlacesList = true;

            if (dlg.ShowDialog() == CommonFileDialogResult.Ok)
            {
                return dlg.FileName;
                // Do something with selected folder string
            }

            return null;
        }

        public static Dispatcher Dispatcher { get; set; }
    }
}