fix[Drag]: fixed drag bug in firefox (#1841)

src/components/DndList/index.vue

@@ -2,7 +2,7 @@
   <div class="dndList">
     <div :style="{width:width1}" class="dndList-list">
       <h3>{{ list1Title }}</h3>
-      <draggable :list="list1" group="article" class="dragArea">
+      <draggable :set-data="setData" :list="list1" group="article" class="dragArea">
         <div v-for="element in list1" :key="element.id" class="list-complete-item">
           <div class="list-complete-item-handle">
             {{ element.id }}[{{ element.author }}] {{ element.title }}
@@ -94,6 +94,11 @@ export default {
       if (this.isNotInList1(ele)) {
         this.list1.push(ele)
       }
+    },
+    setData(dataTransfer) {
+      // to avoid Firefox bug
+      // Detail see : https://github.com/RubaXa/Sortable/issues/1012
+      dataTransfer.setData('Text', '')
     }
   }
 }