Using the uploader with ASP.NET MVC 3 (Razor), I have configured the uploader like this:

        private void InitializeUploader(MvcUploader uploader)

        {

            uploader.UploadUrl = Response.ApplyAppPathModifier("~/UploadHandler.ashx");

            uploader.Name = "testFileUploader";

            uploader.MultipleFilesUpload = true;

            uploader.InsertText = "Add Files";

            uploader.InsertButtonID = "testFileSelector";

            uploader.AllowedFileExtensions = "xsd,xml";

            uploader.MaxSizeKB = 2097151;

        }

Then when the file dialog is pointed at a directory with both XML and XSD files, only the XML files are visible:

Notice the drop down above the "open" and "cancel" buttons reads "(*.xml,*.xml)".

Is my configuration incorrect? Or am I missing something?

When you select the "All Files" filter you see there is in fact an XSD file in the directory: