Allow using mouse wheel to navigate through the emoji tabs

src/components/emoji_picker/emoji_picker.js

@@ -62,6 +62,10 @@ const EmojiPicker = {
       this.scrolledGroup(target)
       this.triggerLoadMore(target)
     },
+    onWheel (e) {
+      e.preventDefault()
+      this.$refs['emoji-tabs'].scrollBy(e.deltaY, 0)
+    },
     highlight (key) {
       this.setShowStickers(false)
       this.activeGroup = key

src/components/emoji_picker/emoji_picker.vue

@@ -1,7 +1,11 @@
 <template>
   <div class="emoji-picker panel panel-default panel-body">
     <div class="heading">
-      <span class="emoji-tabs">
+      <span
+        class="emoji-tabs"
+        @wheel="onWheel"
+        ref="emoji-tabs"
+      >
         <span
           v-for="group in emojis"
           :key="group.id"