Maybe not an issue with hypeDropzone alone. It looks like Elgg itself creates these extra folders. While trying to understand what your problem is I noticed that these extra folders seem to appear on uploading files with the bundled Files plugin (and not only on image uploads but with all kinds of files). I suspect it is connected with the new file upload API introduced in Elgg 2.3. Maybe the upload process does not clean up completely after the work is done.

I've opened an issue about it at https://github.com/Elgg/Elgg/issues/11445.

For what it's worth, the filedrop function used in hypeGallery must be a different method because it saves new icons in the "...<owner_guid>/icons" folder.  I've spent a lot of time comparing the two plugins to discern what's different, but it exhausted my skill set.  Passing 'action' => 'action/gallery/upload/filedrop' to the input/dropzone view allows hypeGallery to control the upload and to put the icons where they should be.

// start.php
elgg_register_plugin_hook_handler('init', 'system', function() {
   elgg_register_ajax_view('partials/form_elements');
});

// views/default/partials/form_elements.php
echo elgg_view_field([
   '#type' => 'date',
]);

echo elgg_view_field([
   '#type' => 'dropzone',
]);

// if using third-party input views, make sure the initialize their scripts inline
// require(['third-party-input']);
// and not using elgg_require_js(), because currently those are not intialized on
// ajax requests

// partial/form_elements.js
define(function(require) {

   var $ = require('jquery');
   var Ajax = require('elgg/Ajax');

   $(document).on('click', '.trigger-element', function(e) {
       e.preventDefault();

       var ajax = new Ajax();
       ajax.view('partials/form_elements').done(function(output) {
          $('.placeholder').append($(output));
       });       
   }); 
});

Thanks.  Great detail.  I'll try it out.

For the sake of others, here is how I implemented your recommendation:

/** plugin/start**/

elgg_register_event_handler('init','system','plugin_init');

function plugin_init() {

   elgg_register_ajax_view('partials/testing');  //Register a view to be available for ajax calls

   elgg_require_js('js/testing');                //Request that Elgg load an AMD module onto the page

}

/**js/testing.js

  * Define function to fire when link is clicked

**/


define(function(require) {


   var $ = require('jquery');

   var Ajax = require('elgg/Ajax');


   $(document).on('click', '.trigger-element-testing', function(e) {

       e.preventDefault();


       var ajax = new Ajax();

   // Define variables to pass

       var field_type = $(this).data("element");                        // Extract field_type from <a ... data_element="<field_type>"</a>

       var entity     = $(this).attr("guid");                           // Extract entity guid from <a ... guid="<entity_guid>"</a>

       var cid        = "c"+Math.floor((Math.random()*200)+1);          // Create a random ID value

   

       ajax.view('partials/testing',{

        data: {                                                       // Pass variables to view

      element: field_type,

      guid: entity,

      cid: cid

        },

       }).done(function(output) {

          $('.placeholder').append($(output));                           // Insert the ajax view after <div class="placeholder"></div>

       });       

   }); 

});

/** site/start
  * 
**/
elgg_register_event_handler('init','system','site_init');

function site_init() {
     $js_framework     = elgg_get_simplecache_url('js' , 'site/framework');
     elgg_require_js($js_framework);
}

/**js/site/framework.php**/

$(document).ready(function(){

$("a.collapser-testing").on("click", function(e) {

e.preventDefault();

$("<div>Collapser clicked</div>").dialog();

});

});

/**partials/testing.php**/
$element = elgg_extract('element', $vars);
$guid    = elgg_extract('guid', $vars);
$cid     = elgg_extract('cid', $vars);
echo "<a class='collapser-testing' tabindex='-1'>Collapser</a><br>";

/**display.testing.php**/

echo '<a href="#" class="elgg-button-submit-element trigger-element-testing" rel="nofollow" data-element="date" guid="45467">+</a>

Here:

<div class="placeholder"><div>

';