I found a curious issue just now. I have a RadAsyncUpload control in an ASP.NET 4.5 project, and the upload works fine, but the FileFilter doesn't seem to be showing until after I've uploaded 1 file.
To be clear:
User clicks "Choose File", the dialog popups like in the attached "before.png" screenshot
or
User clicks Cancel on that popup and clicks "Choose File" again, and it appears again like in the attached "before.png" screenshot
However if the user actually selects a file and the file is uploaded, clicking on "Choose File" again, the user is presented with a dialog as shown in the "after.png" screenshot.
To be clear:
User clicks "Choose File", the dialog popups like in the attached "before.png" screenshot
or
User clicks Cancel on that popup and clicks "Choose File" again, and it appears again like in the attached "before.png" screenshot
However if the user actually selects a file and the file is uploaded, clicking on "Choose File" again, the user is presented with a dialog as shown in the "after.png" screenshot.