diff --git a/dist/amd/dragula.js b/dist/amd/dragula.js
index 4ce811b..efc0a78 100644
--- a/dist/amd/dragula.js
+++ b/dist/amd/dragula.js
@@ -1,4 +1,4 @@
-define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/class-call-check', 'aurelia-dependency-injection', './touchy', './options', './util', 'contra', 'crossvent', './classes'], function (exports, _babelRuntimeHelpersCreateClass, _babelRuntimeHelpersClassCallCheck, _aureliaDependencyInjection, _touchy, _options, _util, _contra, _crossvent, _classes) {
+define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/class-call-check', 'aurelia-dependency-injection', './touchy', './options', './util', './emitter', './classes'], function (exports, _babelRuntimeHelpersCreateClass, _babelRuntimeHelpersClassCallCheck, _aureliaDependencyInjection, _touchy, _options, _util, _emitter, _classes) {
   'use strict';
 
   Object.defineProperty(exports, '__esModule', {
@@ -11,7 +11,8 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
 
       var len = arguments.length;
       this.options = options || new _options.Options();
-      this.drake = (0, _contra.emitter)({
+      this.emitter = new _emitter.Emitter();
+      this.drake = {
         containers: this.options.containers,
         start: this.manualStart.bind(this),
         end: this.end.bind(this),
@@ -19,10 +20,11 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         remove: this.remove.bind(this),
         destroy: this.destroy.bind(this),
         dragging: false
-      });
+      };
 
       if (this.options.removeOnSpill === true) {
-        this.drake.on('over', spillOver).on('out', spillOut);
+        this.emitter.on('over', this.spillOver.bind(this));
+        this.emitter.on('out', this.spillOut.bind(this));
       }
 
       this._events();
@@ -45,7 +47,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
     (0, _babelRuntimeHelpersCreateClass['default'])(Dragula, [{
       key: 'on',
       value: function on(eventName, callback) {
-        this.drake.on(eventName, callback);
+        this.emitter.on(eventName, callback);
       }
     }, {
       key: 'isContainer',
@@ -55,22 +57,21 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
     }, {
       key: '_events',
       value: function _events(remove) {
-        var op = remove ? 'remove' : 'add';
+        var op = remove ? 'removeEventListener' : 'addEventListener';
         (0, _touchy.touchy)(document.documentElement, op, 'mousedown', this._grab.bind(this));
         (0, _touchy.touchy)(document.documentElement, op, 'mouseup', this._release.bind(this));
       }
     }, {
       key: '_eventualMovements',
       value: function _eventualMovements(remove) {
-        var op = remove ? 'remove' : 'add';
+        var op = remove ? 'removeEventListener' : 'addEventListener';
         (0, _touchy.touchy)(document.documentElement, op, 'mousemove', this._startBecauseMouseMoved.bind(this));
       }
     }, {
       key: '_movements',
       value: function _movements(remove) {
-        var op = remove ? 'remove' : 'add';
-        _crossvent[op](document.documentElement, 'selectstart', this._preventGrabbed);
-        _crossvent[op](document.documentElement, 'click', this._preventGrabbed);
+        var op = remove ? 'removeEventListener' : 'addEventListener';
+        document.documentElement[op]('click', this._preventGrabbed);
       }
     }, {
       key: 'destroy',
@@ -197,7 +198,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
       value: function start(context) {
         if (this._isCopy(context.item, context.source)) {
           this._copy = context.item.cloneNode(true);
-          this.drake.emit('cloned', this._copy, context.item, 'copy');
+          this.emitter.emit('cloned', this._copy, context.item, 'copy');
         }
 
         this._source = context.source;
@@ -205,7 +206,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         this._initialSibling = this._currentSibling = _util.Util.nextEl(context.item);
 
         this.drake.dragging = true;
-        this.drake.emit('drag', this._item, this._source);
+        this.emitter.emit('drag', this._item, this._source);
       }
     }, {
       key: 'end',
@@ -252,9 +253,9 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
           parent.removeChild(_item);
         }
         if (this._isInitialPlacement(target)) {
-          this.drake.emit('cancel', item, this._source, this._source);
+          this.emitter.emit('cancel', item, this._source, this._source);
         } else {
-          this.drake.emit('drop', item, target, this._source, this._currentSibling);
+          this.emitter.emit('drop', item, target, this._source, this._currentSibling);
         }
         this._cleanup();
       }
@@ -269,7 +270,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         if (parent) {
           parent.removeChild(item);
         }
-        this.drake.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
+        this.emitter.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
         this._cleanup();
       }
     }, {
@@ -289,9 +290,9 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
           this._source.insertBefore(item, this._initialSibling);
         }
         if (initial || reverts) {
-          this.drake.emit('cancel', item, this._source, this._source);
+          this.emitter.emit('cancel', item, this._source, this._source);
         } else {
-          this.drake.emit('drop', item, parent, this._source, this._currentSibling);
+          this.emitter.emit('drop', item, parent, this._source, this._currentSibling);
         }
         this._cleanup();
       }
@@ -309,9 +310,9 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         }
         this.drake.dragging = false;
         if (this._lastDropTarget) {
-          this.drake.emit('out', item, this._lastDropTarget, this._source);
+          this.emitter.emit('out', item, this._lastDropTarget, this._source);
         }
-        this.drake.emit('dragend', item);
+        this.emitter.emit('dragend', item);
         this._source = this._item = this._copy = this._initialSibling = this._currentSibling = this._renderTimer = this._lastDropTarget = null;
       }
     }, {
@@ -364,7 +365,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         e.preventDefault();
 
         var moved = function moved(type) {
-          _this2.drake.emit(type, item, _this2._lastDropTarget, _this2._source);
+          _this2.emitter.emit(type, item, _this2._lastDropTarget, _this2._source);
         };
         var over = function over() {
           if (changed) {
@@ -417,7 +418,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         if (reference === null && changed || reference !== item && reference !== _util.Util.nextEl(item)) {
           this._currentSibling = reference;
           dropTarget.insertBefore(item, reference);
-          this.drake.emit('shadow', item, dropTarget, this._source);
+          this.emitter.emit('shadow', item, dropTarget, this._source);
         }
       }
     }, {
@@ -445,16 +446,16 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
         _classes.rm(this._mirror, 'gu-transit');
         _classes.add(this._mirror, 'gu-mirror');
         this.options.mirrorContainer.appendChild(this._mirror);
-        (0, _touchy.touchy)(document.documentElement, 'add', 'mousemove', this.drag.bind(this));
+        (0, _touchy.touchy)(document.documentElement, 'addEventListener', 'mousemove', this.drag.bind(this));
         _classes.add(this.options.mirrorContainer, 'gu-unselectable');
-        this.drake.emit('cloned', this._mirror, this._item, 'mirror');
+        this.emitter.emit('cloned', this._mirror, this._item, 'mirror');
       }
     }, {
       key: 'removeMirrorImage',
       value: function removeMirrorImage() {
         if (this._mirror) {
           _classes.rm(this.options.mirrorContainer, 'gu-unselectable');
-          (0, _touchy.touchy)(document.documentElement, 'remove', 'mousemove', this.drag.bind(this));
+          (0, _touchy.touchy)(document.documentElement, 'removeEventListener', 'mousemove', this.drag.bind(this));
           _util.Util.getParent(this._mirror).removeChild(this._mirror);
           this._mirror = null;
         }
@@ -462,11 +463,7 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
     }, {
       key: 'getReference',
       value: function getReference(dropTarget, target, x, y) {
-        var horizontal = this.options.direction === 'horizontal';
-        var reference = target !== dropTarget ? inside() : outside();
-        return reference;
-
-        outside = function () {
+        var outside = function outside() {
           var len = dropTarget.children.length;
           var i = undefined;
           var el = undefined;
@@ -484,17 +481,21 @@ define(['exports', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/
           return null;
         };
 
-        inside = function () {
+        var resolve = function resolve(after) {
+          return after ? _util.Util.nextEl(target) : target;
+        };
+
+        var inside = function inside() {
           var rect = target.getBoundingClientRect();
           if (horizontal) {
-            return resolve(x > rect.left + getRectWidth(rect) / 2);
+            return resolve(x > rect.left + _util.Util.getRectWidth(rect) / 2);
           }
-          return resolve(y > rect.top + getRectHeight(rect) / 2);
+          return resolve(y > rect.top + _util.Util.getRectHeight(rect) / 2);
         };
 
-        resolve = function (after) {
-          return after ? _util.Util.nextEl(target) : target;
-        };
+        var horizontal = this.options.direction === 'horizontal';
+        var reference = target !== dropTarget ? inside() : outside();
+        return reference;
       }
     }, {
       key: '_isCopy',
diff --git a/dist/amd/emitter.js b/dist/amd/emitter.js
new file mode 100644
index 0000000..6a6bea5
--- /dev/null
+++ b/dist/amd/emitter.js
@@ -0,0 +1,91 @@
+define(['exports', 'babel-runtime/helpers/class-call-check', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/slice', 'babel-runtime/helpers/to-consumable-array'], function (exports, _babelRuntimeHelpersClassCallCheck, _babelRuntimeHelpersCreateClass, _babelRuntimeHelpersSlice, _babelRuntimeHelpersToConsumableArray) {
+  'use strict';
+
+  Object.defineProperty(exports, '__esModule', {
+    value: true
+  });
+
+  var EventListener = function EventListener(func) {
+    var once = arguments.length <= 1 || arguments[1] === undefined ? false : arguments[1];
+    (0, _babelRuntimeHelpersClassCallCheck['default'])(this, EventListener);
+
+    this.func = func;
+    this.once = once;
+  };
+
+  var Emitter = (function () {
+    function Emitter(options) {
+      (0, _babelRuntimeHelpersClassCallCheck['default'])(this, Emitter);
+
+      this.options = options || {};
+      this.events = {};
+    }
+
+    (0, _babelRuntimeHelpersCreateClass['default'])(Emitter, [{
+      key: 'on',
+      value: function on(type, fn) {
+        var once = arguments.length <= 2 || arguments[2] === undefined ? false : arguments[2];
+
+        var newEvent = new EventListener(fn, once);
+        if (this.events[type] === undefined) {
+          this.events[type] = [];
+        }
+        this.events[type].push(newEvent);
+      }
+    }, {
+      key: 'once',
+      value: function once(type, fn) {
+        this.on(type, fn, true);
+      }
+    }, {
+      key: 'off',
+      value: function off(type, fn) {
+        if (arguments.length === 1) {
+          delete this.events[type];
+        } else if (arguments.length === 0) {
+          this.events = {};
+        } else {
+          var eventList = this.events[type];
+          if (eventList) {
+            var index = eventList.findIndex(function (x) {
+              return x.func === fn;
+            });
+            if (index >= 0) eventList.splice(index, 1);
+          }
+        }
+      }
+    }, {
+      key: 'emit',
+      value: function emit() {
+        var args = [].concat(_babelRuntimeHelpersSlice['default'].call(arguments));
+        return this._emitterSnapshot(args.shift()).apply(this, args);
+      }
+    }, {
+      key: '_emitterSnapshot',
+      value: function _emitterSnapshot(type) {
+        var et = (this.events[type] || []).slice(0);
+        return function () {
+          var _this = this;
+
+          var args = arguments ? [].concat(_babelRuntimeHelpersSlice['default'].call(arguments)) : [];
+          if (type === 'error' && this.options.throws !== false && !et.length) {
+            throw args.length === 1 ? args[0] : args;
+          }
+          et.forEach(function (listener) {
+            if (_this.options.async) {
+              debounce.apply(undefined, [listener.func].concat((0, _babelRuntimeHelpersToConsumableArray['default'])(args)));
+            } else {
+              listener.func.apply(listener, (0, _babelRuntimeHelpersToConsumableArray['default'])(args));
+            }
+            if (listener.once) {
+              _this.off(type, listener);
+            }
+          });
+        };
+      }
+    }]);
+    return Emitter;
+  })();
+
+  exports.Emitter = Emitter;
+});
\ No newline at end of file
diff --git a/dist/amd/index.js b/dist/amd/index.js
index 2cd3253..ee73d40 100644
--- a/dist/amd/index.js
+++ b/dist/amd/index.js
@@ -6,6 +6,7 @@ define(['exports', './options', './dragula'], function (exports, _options, _drag
   });
   exports.configure = configure;
   exports.Dragula = _dragula.Dragula;
+  exports.Options = _options.Options;
 
   function configure(config, callback) {
     var defaults = new _options.Options();
diff --git a/dist/amd/touchy.js b/dist/amd/touchy.js
index cfc1263..1739c32 100644
--- a/dist/amd/touchy.js
+++ b/dist/amd/touchy.js
@@ -1,11 +1,10 @@
-define(['exports', 'crossvent'], function (exports, _crossvent) {
+define(['exports'], function (exports) {
   'use strict';
 
   Object.defineProperty(exports, '__esModule', {
     value: true
   });
   exports.touchy = touchy;
-
   var touch = {
     mouseup: 'touchend',
     mousedown: 'touchstart',
@@ -24,12 +23,12 @@ define(['exports', 'crossvent'], function (exports, _crossvent) {
 
   function touchy(el, op, type, fn) {
     if (window.navigator.pointerEnabled) {
-      _crossvent[op](el, pointers[type], fn);
+      el[op](pointers[type], fn);
     } else if (window.navigator.msPointerEnabled) {
-      _crossvent[op](el, microsoft[type], fn);
+      el[op](microsoft[type], fn);
     } else {
-      _crossvent[op](el, touch[type], fn);
-      _crossvent[op](el, type, fn);
+      el[op](touch[type], fn);
+      el[op](type, fn);
     }
   }
 });
\ No newline at end of file
diff --git a/dist/commonjs/dragula.js b/dist/commonjs/dragula.js
index 205e86f..840d71b 100644
--- a/dist/commonjs/dragula.js
+++ b/dist/commonjs/dragula.js
@@ -18,11 +18,7 @@ var _options = require('./options');
 
 var _util = require('./util');
 
-var _contra = require('contra');
-
-var _crossvent = require('crossvent');
-
-var crossvent = _interopRequireWildcard(_crossvent);
+var _emitter = require('./emitter');
 
 var _classes = require('./classes');
 
@@ -34,7 +30,8 @@ var Dragula = (function () {
 
     var len = arguments.length;
     this.options = options || new _options.Options();
-    this.drake = (0, _contra.emitter)({
+    this.emitter = new _emitter.Emitter();
+    this.drake = {
       containers: this.options.containers,
       start: this.manualStart.bind(this),
       end: this.end.bind(this),
@@ -42,10 +39,11 @@ var Dragula = (function () {
       remove: this.remove.bind(this),
       destroy: this.destroy.bind(this),
       dragging: false
-    });
+    };
 
     if (this.options.removeOnSpill === true) {
-      this.drake.on('over', spillOver).on('out', spillOut);
+      this.emitter.on('over', this.spillOver.bind(this));
+      this.emitter.on('out', this.spillOut.bind(this));
     }
 
     this._events();
@@ -68,7 +66,7 @@ var Dragula = (function () {
   _createClass(Dragula, [{
     key: 'on',
     value: function on(eventName, callback) {
-      this.drake.on(eventName, callback);
+      this.emitter.on(eventName, callback);
     }
   }, {
     key: 'isContainer',
@@ -78,22 +76,21 @@ var Dragula = (function () {
   }, {
     key: '_events',
     value: function _events(remove) {
-      var op = remove ? 'remove' : 'add';
+      var op = remove ? 'removeEventListener' : 'addEventListener';
       (0, _touchy.touchy)(document.documentElement, op, 'mousedown', this._grab.bind(this));
       (0, _touchy.touchy)(document.documentElement, op, 'mouseup', this._release.bind(this));
     }
   }, {
     key: '_eventualMovements',
     value: function _eventualMovements(remove) {
-      var op = remove ? 'remove' : 'add';
+      var op = remove ? 'removeEventListener' : 'addEventListener';
       (0, _touchy.touchy)(document.documentElement, op, 'mousemove', this._startBecauseMouseMoved.bind(this));
     }
   }, {
     key: '_movements',
     value: function _movements(remove) {
-      var op = remove ? 'remove' : 'add';
-      crossvent[op](document.documentElement, 'selectstart', this._preventGrabbed);
-      crossvent[op](document.documentElement, 'click', this._preventGrabbed);
+      var op = remove ? 'removeEventListener' : 'addEventListener';
+      document.documentElement[op]('click', this._preventGrabbed);
     }
   }, {
     key: 'destroy',
@@ -220,7 +217,7 @@ var Dragula = (function () {
     value: function start(context) {
       if (this._isCopy(context.item, context.source)) {
         this._copy = context.item.cloneNode(true);
-        this.drake.emit('cloned', this._copy, context.item, 'copy');
+        this.emitter.emit('cloned', this._copy, context.item, 'copy');
       }
 
       this._source = context.source;
@@ -228,7 +225,7 @@ var Dragula = (function () {
       this._initialSibling = this._currentSibling = _util.Util.nextEl(context.item);
 
       this.drake.dragging = true;
-      this.drake.emit('drag', this._item, this._source);
+      this.emitter.emit('drag', this._item, this._source);
     }
   }, {
     key: 'end',
@@ -275,9 +272,9 @@ var Dragula = (function () {
         parent.removeChild(_item);
       }
       if (this._isInitialPlacement(target)) {
-        this.drake.emit('cancel', item, this._source, this._source);
+        this.emitter.emit('cancel', item, this._source, this._source);
       } else {
-        this.drake.emit('drop', item, target, this._source, this._currentSibling);
+        this.emitter.emit('drop', item, target, this._source, this._currentSibling);
       }
       this._cleanup();
     }
@@ -292,7 +289,7 @@ var Dragula = (function () {
       if (parent) {
         parent.removeChild(item);
       }
-      this.drake.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
+      this.emitter.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
       this._cleanup();
     }
   }, {
@@ -312,9 +309,9 @@ var Dragula = (function () {
         this._source.insertBefore(item, this._initialSibling);
       }
       if (initial || reverts) {
-        this.drake.emit('cancel', item, this._source, this._source);
+        this.emitter.emit('cancel', item, this._source, this._source);
       } else {
-        this.drake.emit('drop', item, parent, this._source, this._currentSibling);
+        this.emitter.emit('drop', item, parent, this._source, this._currentSibling);
       }
       this._cleanup();
     }
@@ -332,9 +329,9 @@ var Dragula = (function () {
       }
       this.drake.dragging = false;
       if (this._lastDropTarget) {
-        this.drake.emit('out', item, this._lastDropTarget, this._source);
+        this.emitter.emit('out', item, this._lastDropTarget, this._source);
       }
-      this.drake.emit('dragend', item);
+      this.emitter.emit('dragend', item);
       this._source = this._item = this._copy = this._initialSibling = this._currentSibling = this._renderTimer = this._lastDropTarget = null;
     }
   }, {
@@ -387,7 +384,7 @@ var Dragula = (function () {
       e.preventDefault();
 
       var moved = function moved(type) {
-        _this2.drake.emit(type, item, _this2._lastDropTarget, _this2._source);
+        _this2.emitter.emit(type, item, _this2._lastDropTarget, _this2._source);
       };
       var over = function over() {
         if (changed) {
@@ -440,7 +437,7 @@ var Dragula = (function () {
       if (reference === null && changed || reference !== item && reference !== _util.Util.nextEl(item)) {
         this._currentSibling = reference;
         dropTarget.insertBefore(item, reference);
-        this.drake.emit('shadow', item, dropTarget, this._source);
+        this.emitter.emit('shadow', item, dropTarget, this._source);
       }
     }
   }, {
@@ -468,16 +465,16 @@ var Dragula = (function () {
       classes.rm(this._mirror, 'gu-transit');
       classes.add(this._mirror, 'gu-mirror');
       this.options.mirrorContainer.appendChild(this._mirror);
-      (0, _touchy.touchy)(document.documentElement, 'add', 'mousemove', this.drag.bind(this));
+      (0, _touchy.touchy)(document.documentElement, 'addEventListener', 'mousemove', this.drag.bind(this));
       classes.add(this.options.mirrorContainer, 'gu-unselectable');
-      this.drake.emit('cloned', this._mirror, this._item, 'mirror');
+      this.emitter.emit('cloned', this._mirror, this._item, 'mirror');
     }
   }, {
     key: 'removeMirrorImage',
     value: function removeMirrorImage() {
       if (this._mirror) {
         classes.rm(this.options.mirrorContainer, 'gu-unselectable');
-        (0, _touchy.touchy)(document.documentElement, 'remove', 'mousemove', this.drag.bind(this));
+        (0, _touchy.touchy)(document.documentElement, 'removeEventListener', 'mousemove', this.drag.bind(this));
         _util.Util.getParent(this._mirror).removeChild(this._mirror);
         this._mirror = null;
       }
@@ -485,11 +482,7 @@ var Dragula = (function () {
   }, {
     key: 'getReference',
     value: function getReference(dropTarget, target, x, y) {
-      var horizontal = this.options.direction === 'horizontal';
-      var reference = target !== dropTarget ? inside() : outside();
-      return reference;
-
-      outside = function () {
+      var outside = function outside() {
         var len = dropTarget.children.length;
         var i = undefined;
         var el = undefined;
@@ -507,17 +500,21 @@ var Dragula = (function () {
         return null;
       };
 
-      inside = function () {
+      var resolve = function resolve(after) {
+        return after ? _util.Util.nextEl(target) : target;
+      };
+
+      var inside = function inside() {
         var rect = target.getBoundingClientRect();
         if (horizontal) {
-          return resolve(x > rect.left + getRectWidth(rect) / 2);
+          return resolve(x > rect.left + _util.Util.getRectWidth(rect) / 2);
         }
-        return resolve(y > rect.top + getRectHeight(rect) / 2);
+        return resolve(y > rect.top + _util.Util.getRectHeight(rect) / 2);
       };
 
-      resolve = function (after) {
-        return after ? _util.Util.nextEl(target) : target;
-      };
+      var horizontal = this.options.direction === 'horizontal';
+      var reference = target !== dropTarget ? inside() : outside();
+      return reference;
     }
   }, {
     key: '_isCopy',
diff --git a/dist/commonjs/emitter.js b/dist/commonjs/emitter.js
new file mode 100644
index 0000000..e491321
--- /dev/null
+++ b/dist/commonjs/emitter.js
@@ -0,0 +1,99 @@
+'use strict';
+
+var _classCallCheck = require('babel-runtime/helpers/class-call-check')['default'];
+
+var _createClass = require('babel-runtime/helpers/create-class')['default'];
+
+var _slice = require('babel-runtime/helpers/slice')['default'];
+
+var _toConsumableArray = require('babel-runtime/helpers/to-consumable-array')['default'];
+
+Object.defineProperty(exports, '__esModule', {
+  value: true
+});
+
+var EventListener = function EventListener(func) {
+  var once = arguments.length <= 1 || arguments[1] === undefined ? false : arguments[1];
+
+  _classCallCheck(this, EventListener);
+
+  this.func = func;
+  this.once = once;
+};
+
+var Emitter = (function () {
+  function Emitter(options) {
+    _classCallCheck(this, Emitter);
+
+    this.options = options || {};
+    this.events = {};
+  }
+
+  _createClass(Emitter, [{
+    key: 'on',
+    value: function on(type, fn) {
+      var once = arguments.length <= 2 || arguments[2] === undefined ? false : arguments[2];
+
+      var newEvent = new EventListener(fn, once);
+      if (this.events[type] === undefined) {
+        this.events[type] = [];
+      }
+      this.events[type].push(newEvent);
+    }
+  }, {
+    key: 'once',
+    value: function once(type, fn) {
+      this.on(type, fn, true);
+    }
+  }, {
+    key: 'off',
+    value: function off(type, fn) {
+      if (arguments.length === 1) {
+        delete this.events[type];
+      } else if (arguments.length === 0) {
+        this.events = {};
+      } else {
+        var eventList = this.events[type];
+        if (eventList) {
+          var index = eventList.findIndex(function (x) {
+            return x.func === fn;
+          });
+          if (index >= 0) eventList.splice(index, 1);
+        }
+      }
+    }
+  }, {
+    key: 'emit',
+    value: function emit() {
+      var args = [].concat(_slice.call(arguments));
+      return this._emitterSnapshot(args.shift()).apply(this, args);
+    }
+  }, {
+    key: '_emitterSnapshot',
+    value: function _emitterSnapshot(type) {
+      var et = (this.events[type] || []).slice(0);
+      return function () {
+        var _this = this;
+
+        var args = arguments ? [].concat(_slice.call(arguments)) : [];
+        if (type === 'error' && this.options.throws !== false && !et.length) {
+          throw args.length === 1 ? args[0] : args;
+        }
+        et.forEach(function (listener) {
+          if (_this.options.async) {
+            debounce.apply(undefined, [listener.func].concat(_toConsumableArray(args)));
+          } else {
+            listener.func.apply(listener, _toConsumableArray(args));
+          }
+          if (listener.once) {
+            _this.off(type, listener);
+          }
+        });
+      };
+    }
+  }]);
+
+  return Emitter;
+})();
+
+exports.Emitter = Emitter;
\ No newline at end of file
diff --git a/dist/commonjs/index.js b/dist/commonjs/index.js
index cdcd1ce..ed58524 100644
--- a/dist/commonjs/index.js
+++ b/dist/commonjs/index.js
@@ -10,6 +10,7 @@ var _options = require('./options');
 var _dragula = require('./dragula');
 
 exports.Dragula = _dragula.Dragula;
+exports.Options = _options.Options;
 
 function configure(config, callback) {
   var defaults = new _options.Options();
diff --git a/dist/commonjs/touchy.js b/dist/commonjs/touchy.js
index 461f607..d11108b 100644
--- a/dist/commonjs/touchy.js
+++ b/dist/commonjs/touchy.js
@@ -1,16 +1,9 @@
 'use strict';
 
-var _interopRequireWildcard = require('babel-runtime/helpers/interop-require-wildcard')['default'];
-
 Object.defineProperty(exports, '__esModule', {
   value: true
 });
 exports.touchy = touchy;
-
-var _crossvent = require('crossvent');
-
-var crossvent = _interopRequireWildcard(_crossvent);
-
 var touch = {
   mouseup: 'touchend',
   mousedown: 'touchstart',
@@ -29,11 +22,11 @@ var microsoft = {
 
 function touchy(el, op, type, fn) {
   if (window.navigator.pointerEnabled) {
-    crossvent[op](el, pointers[type], fn);
+    el[op](pointers[type], fn);
   } else if (window.navigator.msPointerEnabled) {
-    crossvent[op](el, microsoft[type], fn);
+    el[op](microsoft[type], fn);
   } else {
-    crossvent[op](el, touch[type], fn);
-    crossvent[op](el, type, fn);
+    el[op](touch[type], fn);
+    el[op](type, fn);
   }
 }
\ No newline at end of file
diff --git a/dist/es6/dragula.js b/dist/es6/dragula.js
index a5691df..f357a76 100644
--- a/dist/es6/dragula.js
+++ b/dist/es6/dragula.js
@@ -2,8 +2,7 @@ import {inject} from 'aurelia-dependency-injection';
 import {touchy} from './touchy';
 import {GLOBAL_OPTIONS, Options} from './options';
 import {Util} from './util';
-import {emitter} from 'contra';
-import * as crossvent from 'crossvent';
+import {Emitter} from './emitter';
 import * as classes from './classes';
 
 
@@ -13,7 +12,8 @@ export class Dragula {
   constructor(options) {
     let len = arguments.length;
     this.options = options || new Options();
-    this.drake = emitter({
+    this.emitter = new Emitter();
+    this.drake = {
       containers: this.options.containers,
       start: ::this.manualStart,
       end: ::this.end,
@@ -21,10 +21,11 @@ export class Dragula {
       remove: ::this.remove,
       destroy: ::this.destroy,
       dragging: false
-    });
+    };
 
     if (this.options.removeOnSpill === true) {
-      this.drake.on('over', spillOver).on('out', spillOut);
+      this.emitter.on('over', ::this.spillOver);
+      this.emitter.on('out', ::this.spillOut);
     }
 
     this._events();
@@ -45,7 +46,7 @@ export class Dragula {
   }
 
   on(eventName, callback) {
-    this.drake.on(eventName, callback);
+    this.emitter.on(eventName, callback);
   }
 
   get containers() {
@@ -65,20 +66,19 @@ export class Dragula {
   }
 
   _events(remove) {
-    let op = remove ? 'remove' : 'add';
+    let op = remove ? 'removeEventListener' : 'addEventListener';
     touchy(document.documentElement, op, 'mousedown', ::this._grab);
     touchy(document.documentElement, op, 'mouseup', ::this._release);
   }
 
   _eventualMovements(remove) {
-    let op = remove ? 'remove' : 'add';
+    let op = remove ? 'removeEventListener' : 'addEventListener';
     touchy(document.documentElement, op, 'mousemove', ::this._startBecauseMouseMoved);
   }
 
   _movements(remove) {
-    let op = remove ? 'remove' : 'add';
-    crossvent[op](document.documentElement, 'selectstart', this._preventGrabbed); // IE8
-    crossvent[op](document.documentElement, 'click', this._preventGrabbed);
+    let op = remove ? 'removeEventListener' : 'addEventListener';
+    document.documentElement[op]('click', this._preventGrabbed);
   }
 
   destroy() {
@@ -198,7 +198,7 @@ export class Dragula {
   start(context) {
     if (this._isCopy(context.item, context.source)) {
       this._copy = context.item.cloneNode(true);
-      this.drake.emit('cloned', this._copy, context.item, 'copy');
+      this.emitter.emit('cloned', this._copy, context.item, 'copy');
     }
 
     this._source = context.source;
@@ -206,7 +206,7 @@ export class Dragula {
     this._initialSibling = this._currentSibling = Util.nextEl(context.item);
 
     this.drake.dragging = true;
-    this.drake.emit('drag', this._item, this._source);
+    this.emitter.emit('drag', this._item, this._source);
   }
 
   end() {
@@ -249,9 +249,9 @@ export class Dragula {
       parent.removeChild(_item);
     }
     if (this._isInitialPlacement(target)) {
-      this.drake.emit('cancel', item, this._source, this._source);
+      this.emitter.emit('cancel', item, this._source, this._source);
     } else {
-      this.drake.emit('drop', item, target, this._source, this._currentSibling);
+      this.emitter.emit('drop', item, target, this._source, this._currentSibling);
     }
     this._cleanup();
   }
@@ -265,7 +265,7 @@ export class Dragula {
     if (parent) {
       parent.removeChild(item);
     }
-    this.drake.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
+    this.emitter.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
     this._cleanup();
   }
 
@@ -284,9 +284,9 @@ export class Dragula {
       this._source.insertBefore(item, this._initialSibling);
     }
     if (initial || reverts) {
-      this.drake.emit('cancel', item, this._source, this._source);
+      this.emitter.emit('cancel', item, this._source, this._source);
     } else {
-      this.drake.emit('drop', item, parent, this._source, this._currentSibling);
+      this.emitter.emit('drop', item, parent, this._source, this._currentSibling);
     }
     this._cleanup();
   }
@@ -303,9 +303,9 @@ export class Dragula {
     }
     this.drake.dragging = false;
     if (this._lastDropTarget) {
-      this.drake.emit('out', item, this._lastDropTarget, this._source);
+      this.emitter.emit('out', item, this._lastDropTarget, this._source);
     }
-    this.drake.emit('dragend', item);
+    this.emitter.emit('dragend', item);
     this._source = this._item = this._copy = this._initialSibling = this._currentSibling = this._renderTimer = this._lastDropTarget = null;
   }
 
@@ -350,7 +350,7 @@ export class Dragula {
     }
     e.preventDefault();
 
-    let moved = (type) => { this.drake.emit(type, item, this._lastDropTarget, this._source); }
+    let moved = (type) => { this.emitter.emit(type, item, this._lastDropTarget, this._source); }
     let over = () => { if (changed) { moved('over'); } }
     let out = () => { if (this._lastDropTarget) { moved('out'); } }
 
@@ -398,7 +398,7 @@ export class Dragula {
     ) {
       this._currentSibling = reference;
       dropTarget.insertBefore(item, reference);
-      this.drake.emit('shadow', item, dropTarget, this._source);
+      this.emitter.emit('shadow', item, dropTarget, this._source);
     }
   }
 
@@ -421,26 +421,22 @@ export class Dragula {
     classes.rm(this._mirror, 'gu-transit');
     classes.add(this._mirror, 'gu-mirror');
     this.options.mirrorContainer.appendChild(this._mirror);
-    touchy(document.documentElement, 'add', 'mousemove', ::this.drag);
+    touchy(document.documentElement, 'addEventListener', 'mousemove', ::this.drag);
     classes.add(this.options.mirrorContainer, 'gu-unselectable');
-    this.drake.emit('cloned', this._mirror, this._item, 'mirror');
+    this.emitter.emit('cloned', this._mirror, this._item, 'mirror');
   }
 
   removeMirrorImage() {
     if (this._mirror) {
       classes.rm(this.options.mirrorContainer, 'gu-unselectable');
-      touchy(document.documentElement, 'remove', 'mousemove', ::this.drag);
+      touchy(document.documentElement, 'removeEventListener', 'mousemove', ::this.drag);
       Util.getParent(this._mirror).removeChild(this._mirror);
       this._mirror = null;
     }
   }
 
   getReference(dropTarget, target, x, y) {
-    let horizontal = this.options.direction === 'horizontal';
-    let reference = target !== dropTarget ? inside() : outside();
-    return reference;
-
-    outside = () => { // slower, but able to figure out any position
+    let outside = () => { // slower, but able to figure out any position
       let len = dropTarget.children.length;
       let i;
       let el;
@@ -454,17 +450,22 @@ export class Dragula {
       return null;
     }
 
-    inside = () => { // faster, but only available if dropped inside a child element
+    let resolve = (after) => {
+      return after ? Util.nextEl(target) : target;
+    }
+
+    let inside = () => { // faster, but only available if dropped inside a child element
       let rect = target.getBoundingClientRect();
       if (horizontal) {
-        return resolve(x > rect.left + getRectWidth(rect) / 2);
+        return resolve(x > rect.left + Util.getRectWidth(rect) / 2);
       }
-      return resolve(y > rect.top + getRectHeight(rect) / 2);
+      return resolve(y > rect.top + Util.getRectHeight(rect) / 2);
     }
 
-    resolve = (after) => {
-      return after ? Util.nextEl(target) : target;
-    }
+
+    let horizontal = this.options.direction === 'horizontal';
+    let reference = target !== dropTarget ? inside() : outside();
+    return reference;
   }
 
   _isCopy(item, container) {
diff --git a/dist/es6/emitter.js b/dist/es6/emitter.js
new file mode 100644
index 0000000..932e704
--- /dev/null
+++ b/dist/es6/emitter.js
@@ -0,0 +1,70 @@
+//let debounce = require('./debounce');
+
+class EventListener {
+
+  constructor(func, once = false) {
+    this.func = func;
+    this.once = once;
+  }
+}
+
+export class Emitter {
+
+  constructor(options) {
+    this.options = options || {};
+    this.events = {};
+  }
+
+  on(type, fn, once = false) {
+    let newEvent = new EventListener(fn, once);
+    if (this.events[type] === undefined) {
+      this.events[type] = [];
+    }
+    this.events[type].push(newEvent);
+  }
+
+  once(type, fn) {
+    this.on(type, fn, true);
+  }
+
+  off(type, fn) {
+    if (arguments.length === 1) {
+      delete this.events[type];
+    }
+    else if (arguments.length === 0) {
+      this.events = {};
+    }
+    else {
+      let eventList = this.events[type];
+      if (eventList) {
+        let index = eventList.findIndex(x => x.func === fn);
+        if (index >= 0)
+          eventList.splice(index, 1);
+      }
+    }
+  }
+
+  emit() {
+    let args = [...arguments];
+    return this._emitterSnapshot(args.shift()).apply(this, args);
+  }
+
+  _emitterSnapshot(type) {
+    let et = (this.events[type] || []).slice(0);
+    return function() {
+      let args = arguments ? [...arguments] : [];
+      if (type === 'error' && this.options.throws !== false && !et.length) { throw args.length === 1 ? args[0] : args; }
+      et.forEach(listener => {
+        if (this.options.async) {
+          debounce(listener.func, ...args);
+        }
+        else {
+          listener.func(...args);
+        }
+        if (listener.once) {
+          this.off(type, listener);
+        }
+      });
+    }
+  }
+}
diff --git a/dist/es6/index.js b/dist/es6/index.js
index da38ce1..2e0dd21 100644
--- a/dist/es6/index.js
+++ b/dist/es6/index.js
@@ -1,7 +1,7 @@
 import {Options, GLOBAL_OPTIONS} from './options';
 
 import {Dragula} from './dragula';
-export {Dragula};
+export {Dragula, Options};
 
 export function configure(config, callback) {
   let defaults = new Options();
diff --git a/dist/es6/touchy.js b/dist/es6/touchy.js
index 045ddd2..03c2d0e 100644
--- a/dist/es6/touchy.js
+++ b/dist/es6/touchy.js
@@ -1,5 +1,3 @@
-import * as crossvent from 'crossvent';
-
 const touch = {
   mouseup: 'touchend',
   mousedown: 'touchstart',
@@ -18,11 +16,11 @@ const microsoft = {
 
 export function touchy(el, op, type, fn) {
   if (window.navigator.pointerEnabled) {
-    crossvent[op](el, pointers[type], fn);
+    el[op](pointers[type], fn);
   } else if (window.navigator.msPointerEnabled) {
-    crossvent[op](el, microsoft[type], fn);
+    el[op](microsoft[type], fn);
   } else {
-    crossvent[op](el, touch[type], fn);
-    crossvent[op](el, type, fn);
+    el[op](touch[type], fn);
+    el[op](type, fn);
   }
 }
\ No newline at end of file
diff --git a/dist/system/dragula.js b/dist/system/dragula.js
index 8faa2f7..36aae3f 100644
--- a/dist/system/dragula.js
+++ b/dist/system/dragula.js
@@ -1,5 +1,5 @@
-System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/class-call-check', 'aurelia-dependency-injection', './touchy', './options', './util', 'contra', 'crossvent', './classes'], function (_export) {
-  var _createClass, _classCallCheck, inject, touchy, GLOBAL_OPTIONS, Options, Util, emitter, crossvent, classes, Dragula;
+System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/class-call-check', 'aurelia-dependency-injection', './touchy', './options', './util', './emitter', './classes'], function (_export) {
+  var _createClass, _classCallCheck, inject, touchy, GLOBAL_OPTIONS, Options, Util, Emitter, classes, Dragula;
 
   return {
     setters: [function (_babelRuntimeHelpersCreateClass) {
@@ -15,10 +15,8 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
       Options = _options.Options;
     }, function (_util) {
       Util = _util.Util;
-    }, function (_contra) {
-      emitter = _contra.emitter;
-    }, function (_crossvent) {
-      crossvent = _crossvent;
+    }, function (_emitter) {
+      Emitter = _emitter.Emitter;
     }, function (_classes) {
       classes = _classes;
     }],
@@ -31,7 +29,8 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
 
           var len = arguments.length;
           this.options = options || new Options();
-          this.drake = emitter({
+          this.emitter = new Emitter();
+          this.drake = {
             containers: this.options.containers,
             start: this.manualStart.bind(this),
             end: this.end.bind(this),
@@ -39,10 +38,11 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             remove: this.remove.bind(this),
             destroy: this.destroy.bind(this),
             dragging: false
-          });
+          };
 
           if (this.options.removeOnSpill === true) {
-            this.drake.on('over', spillOver).on('out', spillOut);
+            this.emitter.on('over', this.spillOver.bind(this));
+            this.emitter.on('out', this.spillOut.bind(this));
           }
 
           this._events();
@@ -65,7 +65,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
         _createClass(Dragula, [{
           key: 'on',
           value: function on(eventName, callback) {
-            this.drake.on(eventName, callback);
+            this.emitter.on(eventName, callback);
           }
         }, {
           key: 'isContainer',
@@ -75,22 +75,21 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
         }, {
           key: '_events',
           value: function _events(remove) {
-            var op = remove ? 'remove' : 'add';
+            var op = remove ? 'removeEventListener' : 'addEventListener';
             touchy(document.documentElement, op, 'mousedown', this._grab.bind(this));
             touchy(document.documentElement, op, 'mouseup', this._release.bind(this));
           }
         }, {
           key: '_eventualMovements',
           value: function _eventualMovements(remove) {
-            var op = remove ? 'remove' : 'add';
+            var op = remove ? 'removeEventListener' : 'addEventListener';
             touchy(document.documentElement, op, 'mousemove', this._startBecauseMouseMoved.bind(this));
           }
         }, {
           key: '_movements',
           value: function _movements(remove) {
-            var op = remove ? 'remove' : 'add';
-            crossvent[op](document.documentElement, 'selectstart', this._preventGrabbed);
-            crossvent[op](document.documentElement, 'click', this._preventGrabbed);
+            var op = remove ? 'removeEventListener' : 'addEventListener';
+            document.documentElement[op]('click', this._preventGrabbed);
           }
         }, {
           key: 'destroy',
@@ -217,7 +216,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
           value: function start(context) {
             if (this._isCopy(context.item, context.source)) {
               this._copy = context.item.cloneNode(true);
-              this.drake.emit('cloned', this._copy, context.item, 'copy');
+              this.emitter.emit('cloned', this._copy, context.item, 'copy');
             }
 
             this._source = context.source;
@@ -225,7 +224,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             this._initialSibling = this._currentSibling = Util.nextEl(context.item);
 
             this.drake.dragging = true;
-            this.drake.emit('drag', this._item, this._source);
+            this.emitter.emit('drag', this._item, this._source);
           }
         }, {
           key: 'end',
@@ -272,9 +271,9 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
               parent.removeChild(_item);
             }
             if (this._isInitialPlacement(target)) {
-              this.drake.emit('cancel', item, this._source, this._source);
+              this.emitter.emit('cancel', item, this._source, this._source);
             } else {
-              this.drake.emit('drop', item, target, this._source, this._currentSibling);
+              this.emitter.emit('drop', item, target, this._source, this._currentSibling);
             }
             this._cleanup();
           }
@@ -289,7 +288,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             if (parent) {
               parent.removeChild(item);
             }
-            this.drake.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
+            this.emitter.emit(this._copy ? 'cancel' : 'remove', item, parent, this._source);
             this._cleanup();
           }
         }, {
@@ -309,9 +308,9 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
               this._source.insertBefore(item, this._initialSibling);
             }
             if (initial || reverts) {
-              this.drake.emit('cancel', item, this._source, this._source);
+              this.emitter.emit('cancel', item, this._source, this._source);
             } else {
-              this.drake.emit('drop', item, parent, this._source, this._currentSibling);
+              this.emitter.emit('drop', item, parent, this._source, this._currentSibling);
             }
             this._cleanup();
           }
@@ -329,9 +328,9 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             }
             this.drake.dragging = false;
             if (this._lastDropTarget) {
-              this.drake.emit('out', item, this._lastDropTarget, this._source);
+              this.emitter.emit('out', item, this._lastDropTarget, this._source);
             }
-            this.drake.emit('dragend', item);
+            this.emitter.emit('dragend', item);
             this._source = this._item = this._copy = this._initialSibling = this._currentSibling = this._renderTimer = this._lastDropTarget = null;
           }
         }, {
@@ -384,7 +383,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             e.preventDefault();
 
             var moved = function moved(type) {
-              _this2.drake.emit(type, item, _this2._lastDropTarget, _this2._source);
+              _this2.emitter.emit(type, item, _this2._lastDropTarget, _this2._source);
             };
             var over = function over() {
               if (changed) {
@@ -437,7 +436,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             if (reference === null && changed || reference !== item && reference !== Util.nextEl(item)) {
               this._currentSibling = reference;
               dropTarget.insertBefore(item, reference);
-              this.drake.emit('shadow', item, dropTarget, this._source);
+              this.emitter.emit('shadow', item, dropTarget, this._source);
             }
           }
         }, {
@@ -465,16 +464,16 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
             classes.rm(this._mirror, 'gu-transit');
             classes.add(this._mirror, 'gu-mirror');
             this.options.mirrorContainer.appendChild(this._mirror);
-            touchy(document.documentElement, 'add', 'mousemove', this.drag.bind(this));
+            touchy(document.documentElement, 'addEventListener', 'mousemove', this.drag.bind(this));
             classes.add(this.options.mirrorContainer, 'gu-unselectable');
-            this.drake.emit('cloned', this._mirror, this._item, 'mirror');
+            this.emitter.emit('cloned', this._mirror, this._item, 'mirror');
           }
         }, {
           key: 'removeMirrorImage',
           value: function removeMirrorImage() {
             if (this._mirror) {
               classes.rm(this.options.mirrorContainer, 'gu-unselectable');
-              touchy(document.documentElement, 'remove', 'mousemove', this.drag.bind(this));
+              touchy(document.documentElement, 'removeEventListener', 'mousemove', this.drag.bind(this));
               Util.getParent(this._mirror).removeChild(this._mirror);
               this._mirror = null;
             }
@@ -482,11 +481,7 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
         }, {
           key: 'getReference',
           value: function getReference(dropTarget, target, x, y) {
-            var horizontal = this.options.direction === 'horizontal';
-            var reference = target !== dropTarget ? inside() : outside();
-            return reference;
-
-            outside = function () {
+            var outside = function outside() {
               var len = dropTarget.children.length;
               var i = undefined;
               var el = undefined;
@@ -504,17 +499,21 @@ System.register(['babel-runtime/helpers/create-class', 'babel-runtime/helpers/cl
               return null;
             };
 
-            inside = function () {
+            var resolve = function resolve(after) {
+              return after ? Util.nextEl(target) : target;
+            };
+
+            var inside = function inside() {
               var rect = target.getBoundingClientRect();
               if (horizontal) {
-                return resolve(x > rect.left + getRectWidth(rect) / 2);
+                return resolve(x > rect.left + Util.getRectWidth(rect) / 2);
               }
-              return resolve(y > rect.top + getRectHeight(rect) / 2);
+              return resolve(y > rect.top + Util.getRectHeight(rect) / 2);
             };
 
-            resolve = function (after) {
-              return after ? Util.nextEl(target) : target;
-            };
+            var horizontal = this.options.direction === 'horizontal';
+            var reference = target !== dropTarget ? inside() : outside();
+            return reference;
           }
         }, {
           key: '_isCopy',
diff --git a/dist/system/emitter.js b/dist/system/emitter.js
new file mode 100644
index 0000000..0bb4d06
--- /dev/null
+++ b/dist/system/emitter.js
@@ -0,0 +1,104 @@
+System.register(['babel-runtime/helpers/class-call-check', 'babel-runtime/helpers/create-class', 'babel-runtime/helpers/slice', 'babel-runtime/helpers/to-consumable-array'], function (_export) {
+  var _classCallCheck, _createClass, _slice, _toConsumableArray, EventListener, Emitter;
+
+  return {
+    setters: [function (_babelRuntimeHelpersClassCallCheck) {
+      _classCallCheck = _babelRuntimeHelpersClassCallCheck['default'];
+    }, function (_babelRuntimeHelpersCreateClass) {
+      _createClass = _babelRuntimeHelpersCreateClass['default'];
+    }, function (_babelRuntimeHelpersSlice) {
+      _slice = _babelRuntimeHelpersSlice['default'];
+    }, function (_babelRuntimeHelpersToConsumableArray) {
+      _toConsumableArray = _babelRuntimeHelpersToConsumableArray['default'];
+    }],
+    execute: function () {
+      'use strict';
+
+      EventListener = function EventListener(func) {
+        var once = arguments.length <= 1 || arguments[1] === undefined ? false : arguments[1];
+
+        _classCallCheck(this, EventListener);
+
+        this.func = func;
+        this.once = once;
+      };
+
+      Emitter = (function () {
+        function Emitter(options) {
+          _classCallCheck(this, Emitter);
+
+          this.options = options || {};
+          this.events = {};
+        }
+
+        _createClass(Emitter, [{
+          key: 'on',
+          value: function on(type, fn) {
+            var once = arguments.length <= 2 || arguments[2] === undefined ? false : arguments[2];
+
+            var newEvent = new EventListener(fn, once);
+            if (this.events[type] === undefined) {
+              this.events[type] = [];
+            }
+            this.events[type].push(newEvent);
+          }
+        }, {
+          key: 'once',
+          value: function once(type, fn) {
+            this.on(type, fn, true);
+          }
+        }, {
+          key: 'off',
+          value: function off(type, fn) {
+            if (arguments.length === 1) {
+              delete this.events[type];
+            } else if (arguments.length === 0) {
+              this.events = {};
+            } else {
+              var eventList = this.events[type];
+              if (eventList) {
+                var index = eventList.findIndex(function (x) {
+                  return x.func === fn;
+                });
+                if (index >= 0) eventList.splice(index, 1);
+              }
+            }
+          }
+        }, {
+          key: 'emit',
+          value: function emit() {
+            var args = [].concat(_slice.call(arguments));
+            return this._emitterSnapshot(args.shift()).apply(this, args);
+          }
+        }, {
+          key: '_emitterSnapshot',
+          value: function _emitterSnapshot(type) {
+            var et = (this.events[type] || []).slice(0);
+            return function () {
+              var _this = this;
+
+              var args = arguments ? [].concat(_slice.call(arguments)) : [];
+              if (type === 'error' && this.options.throws !== false && !et.length) {
+                throw args.length === 1 ? args[0] : args;
+              }
+              et.forEach(function (listener) {
+                if (_this.options.async) {
+                  debounce.apply(undefined, [listener.func].concat(_toConsumableArray(args)));
+                } else {
+                  listener.func.apply(listener, _toConsumableArray(args));
+                }
+                if (listener.once) {
+                  _this.off(type, listener);
+                }
+              });
+            };
+          }
+        }]);
+
+        return Emitter;
+      })();
+
+      _export('Emitter', Emitter);
+    }
+  };
+});
\ No newline at end of file
diff --git a/dist/system/index.js b/dist/system/index.js
index eee5d3c..eed032c 100644
--- a/dist/system/index.js
+++ b/dist/system/index.js
@@ -23,6 +23,8 @@ System.register(['./options', './dragula'], function (_export) {
     }],
     execute: function () {
       _export('Dragula', Dragula);
+
+      _export('Options', Options);
     }
   };
 });
\ No newline at end of file
diff --git a/dist/system/touchy.js b/dist/system/touchy.js
index a942a02..f6560b2 100644
--- a/dist/system/touchy.js
+++ b/dist/system/touchy.js
@@ -1,25 +1,23 @@
-System.register(['crossvent'], function (_export) {
+System.register([], function (_export) {
   'use strict';
 
-  var crossvent, touch, pointers, microsoft;
+  var touch, pointers, microsoft;
 
   _export('touchy', touchy);
 
   function touchy(el, op, type, fn) {
     if (window.navigator.pointerEnabled) {
-      crossvent[op](el, pointers[type], fn);
+      el[op](pointers[type], fn);
     } else if (window.navigator.msPointerEnabled) {
-      crossvent[op](el, microsoft[type], fn);
+      el[op](microsoft[type], fn);
     } else {
-      crossvent[op](el, touch[type], fn);
-      crossvent[op](el, type, fn);
+      el[op](touch[type], fn);
+      el[op](type, fn);
     }
   }
 
   return {
-    setters: [function (_crossvent) {
-      crossvent = _crossvent;
-    }],
+    setters: [],
     execute: function () {
       touch = {
         mouseup: 'touchend',