add allDraggable option for timeline to support dragging unselected item

lib/timeline/component/ItemSet.js

@@ -43,6 +43,7 @@ function ItemSet(body, options) {
 
     selectable: true,
     multiselect: false,
+    allDraggable: false,
 
     editable: {
       updateTime: false,
@@ -307,7 +308,7 @@ ItemSet.prototype._create = function(){
 ItemSet.prototype.setOptions = function(options) {
   if (options) {
     // copy all options that we know
-    var fields = ['type', 'align', 'order', 'stack', 'selectable', 'multiselect', 'multiselectPerGroup', 'groupOrder', 'dataAttributes', 'template', 'groupTemplate', 'hide', 'snap', 'groupOrderSwap'];
+    var fields = ['type', 'align', 'order', 'stack', 'selectable', 'multiselect', 'allDraggable', 'multiselectPerGroup', 'groupOrder', 'dataAttributes', 'template', 'groupTemplate', 'hide', 'snap', 'groupOrderSwap'];
     util.selectiveExtend(fields, this.options, options);
 
     if ('orientation' in options) {
@@ -1172,7 +1173,7 @@ ItemSet.prototype._onDragStart = function (event) {
   var me = this;
   var props;
 
-  if (item && item.selected) {
+  if (item && (item.selected || this.options.allDraggable)) {
 
     if (!this.options.editable.updateTime &&
         !this.options.editable.updateGroup &&
@@ -1213,7 +1214,9 @@ ItemSet.prototype._onDragStart = function (event) {
 
       var baseGroupIndex = this._getGroupIndex(item.data.group);
 
-      this.touchParams.itemProps = this.getSelection().map(function (id) {
+      var itemsToDrag = (this.options.allDraggable && !item.selected) ? [item.id] : this.getSelection();
+
+      this.touchParams.itemProps = itemsToDrag.map(function (id) {
         var item = me.items[id];
         var groupIndex = me._getGroupIndex(item.data.group);
         return {

lib/timeline/optionsTimeline.js

@@ -26,6 +26,7 @@ let allOptions = {
 
   //globals :
   align: {string},
+  allDraggable: { boolean: boolean },
   autoResize: {boolean},
   throttleRedraw: {number},
   clickToUse: {boolean},