title: Modifying a draft without downloading attachments
body: <p>I have a draft saved on my Gmail account, containing an attachment. At a later stage, I realise that I have to add some text to the mail, via the Gmail API. At an even later stage, I decide to send the draft. From what I've found, the only way to do this is to:</p>
  
  <ol>
  <li>Download the draft and decode it.</li>
  <li>Edit the message body to your liking.</li>
  <li>Encode it and save the draft.</li>
  <li>Send the draft.</li>
  </ol>
  
  <p>This is all well and good, until you have a big attachment in your draft. Is there another way than doing the steps outlined above with the <a href="https://developers.google.com/gmail/api/v1/reference/users/drafts/update" rel="nofollow">Users.draft: update</a>, so that you don't have to download the attachments when you just want to alter the message?</p>
  
  <p>Thanks.</p>