Sending Twitter - Synthetic ClipboardData with File

Add-ons Development
#1

I’m trying to attach images to the twitter - new tweet. If you copy a file from your OS then go to the twitter body area and paste it, it will attach it. As per this image:

sqA3MOU.gif834×480 1.29 MB

So i used devTools to inspect the clipboard event and this is what i see:

Inspecting that clipboardEvent we see:

Man i wish you could copy from this inspector.

So in Files and Types we see:

function sendTwitterPasteEvent() {
    
    var aContentWindow = gBrowser.contentWindow;
    var aContentDocument = aContentWindow.document;
    
    var btnNewTweet = aContentDocument.getElementById('global-new-tweet-button');
    console.info('btnNewTweet:', btnNewTweet);
    if (!btnNewTweet) {
        throw new Error('global tweet button not found, probably not logged in');
    }

    btnNewTweet.click();
  
  var richInputTweetMsg = aContentDocument.getElementById('tweet-box-global');
  // richInputTweetMsg.focus();
  
  var pasteEvent = new aContentWindow.ClipboardEvent('paste', {bubbles:true,cancelable:true});

  var file = new File('C:\\Users\\Vayeate\\Pictures\\Screenshot - Tuesday, August 11, 2015 6-33-58 AM.png');
    pasteEvent.clipboardData.mozSetDataAt("application/x-moz-file", file, 0);
    
    console.info('pasteEvent:', pasteEvent);
    
  richInputTweetMsg.dispatchEvent(pasteEvent);
  
}

sendTwitterPasteEvent();

If you sign in to twitter, and run this code from scratchpad borwser environment, it will open the tweet modal, then try to paste. The transefer data in debugger tools shows my pasteEvent is exactly the same as the native paste event with a real file on clipboard, but my image is not going through. Can anyone help? Im on irc as noida if anyone wants to work with me on this a little mroe closely.

#2

Edit - removed
I added it into the post above as this method makes the DataTransfer of my synthetic clipboard event be same as if it were native, however the Twitter thing is not taking (even though every step with debugger tools shows datattransfeer objects are same)

#3

In my experience faking events is notoriously unreliable.