Download of uploaded file from submission page fails when files are private

(First, the file upload component is a great enhancement to webform. Thanks for making it available.)

When viewing a webform submission, a file uploaded via the file component is made available to download via link. Unfortunately, when private files are operating (administer / settings / File system settings) the path provided by webform leads to a page not found error.

My understanding is that webform needs to make the file download link include system/files/, e.g. http://example.com/system/files/webform/example.pdf and implement hook_download function.

function webform_file_download($file) would test to see whether the requested file is managed by webform (and do nothing if the file belongs to another module such as og or fileshare). If the file is managed by webform, then determine whether the user has access to the file (e.g. via node_access().

If my client ok's it, I may implement this, but I'll flag the issue in case I don't get approval to work on it.