Fixed scrollability not being obvious, added fade effect

src/components/emoji_picker/emoji_picker.js

@@ -17,6 +17,7 @@ const EmojiPicker = {
       keyword: '',
       activeGroup: 'custom',
       showingStickers: false,
+      groupsScrolledClass: 'scrolled-top',
       spamMode: false
     }
   },
@@ -40,6 +41,13 @@ const EmojiPicker = {
     scrolledGroup (e) {
       const target = (e && e.target) || this.$refs['emoji-groups']
       const top = target.scrollTop + 5
+      if (target.scrollTop <= 5) {
+        this.groupsScrolledClass = 'scrolled-top'
+      } else if (target.scrollTop >= target.scrollTopMax - 5) {
+        this.groupsScrolledClass = 'scrolled-bottom'
+      } else {
+        this.groupsScrolledClass = 'scrolled-middle'
+      }
       this.$nextTick(() => {
         this.emojisView.forEach(group => {
           const ref = this.$refs['group-' + group.id]

src/components/emoji_picker/emoji_picker.scss

@@ -6,7 +6,7 @@
   position: absolute;
   right: 0;
   left: 0;
-  height: 300px;
+  height: 320px;
   margin: 0 !important;
   z-index: 1;
 
@@ -104,6 +104,22 @@
       flex: 1 1 1px;
       position: relative;
       overflow: auto;
+      mask: linear-gradient(to top, white 0, transparent 100%) bottom no-repeat,
+            linear-gradient(to bottom, white 0, transparent 100%) top no-repeat,
+            linear-gradient(to top, white, white);
+      transition: mask-size 150ms;
+      mask-size: 100% 20px, 100% 20px, auto;
+      // Autoprefixed seem to ignore this one, and also syntax is different
+      -webkit-mask-composite: xor;
+      mask-composite: exclude;
+      &.scrolled {
+        &-top {
+          mask-size: 100% 20px, 100% 0, auto;
+        }
+        &-bottom {
+          mask-size: 100% 0, 100% 20px, auto;
+        }
+      }
     }
 
     &-group {

src/components/emoji_picker/emoji_picker.vue

@@ -46,6 +46,7 @@
         <div
           ref="emoji-groups"
           class="emoji-groups"
+          :class="groupsScrolledClass"
           @scroll="scrolledGroup"
         >
           <div