Fix sticker pack preview modal scrollbars and modal scroll dividers

stylesheets/components/Modal.scss

@@ -125,10 +125,10 @@
   &--has-header#{&}--header-divider {
     .module-Modal__body {
       @include light-theme() {
-        border-top-color: $color-gray-15;
+        border-top-color: $color-gray-05;
       }
       @include dark-theme() {
-        border-top-color: $color-gray-60;
+        border-top-color: $color-gray-90;
       }
     }
   }
@@ -137,6 +137,7 @@
     .module-Modal__body {
       padding-top: 0;
       border-top: 1px solid transparent;
+      border-bottom: 1px solid transparent;
 
       &--scrolled {
         @include light-theme {
@@ -144,7 +145,7 @@
         }
 
         @include dark-theme {
-          border-top-color: $color-gray-80;
+          border-top-color: $color-gray-90;
         }
       }
     }
@@ -153,10 +154,10 @@
   &--has-footer#{&}--footer-divider {
     .module-Modal__body {
       @include light-theme() {
-        border-bottom-color: $color-gray-15;
+        border-bottom-color: $color-gray-05;
       }
       @include dark-theme() {
-        border-bottom-color: $color-gray-60;
+        border-bottom-color: $color-gray-90;
       }
     }
   }
@@ -164,6 +165,16 @@
   &--has-footer {
     .module-Modal__body {
       border-bottom: 1px solid transparent;
+
+      &--overflow:not(&--scrolledToBottom) {
+        @include light-theme {
+          border-bottom-color: $color-gray-05;
+        }
+
+        @include dark-theme {
+          border-bottom-color: $color-gray-90;
+        }
+      }
     }
   }
 

stylesheets/components/StickerManager.scss

@@ -217,8 +217,7 @@
 
 .module-sticker-manager__preview-modal {
   &__modal.module-Modal {
-    max-width: 440px;
-    width: 440px;
+    width: fit-content;
   }
   &__error {
     color: $color-accent-red;
@@ -239,7 +238,6 @@
     display: grid;
     grid-gap: 8px;
     grid-template-columns: repeat(4, 1fr);
-    overflow-y: auto;
 
     &__cell {
       width: 96px;

ts/components/AddCaptionModal.tsx

@@ -1,13 +1,14 @@
 // Copyright 2022 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import React, { useEffect } from 'react';
+import React from 'react';
 import { noop } from 'lodash';
 import { Button } from './Button';
 import { Modal } from './Modal';
 import type { LocalizerType, ThemeType } from '../types/Util';
 import type { SmartCompositionTextAreaProps } from '../state/smart/CompositionTextArea';
 import type { HydratedBodyRangesType } from '../types/BodyRange';
+import { isScrolled, isScrolledToBottom } from '../hooks/useSizeObserver';
 
 export type Props = {
   i18n: LocalizerType;
@@ -38,8 +39,9 @@ export function AddCaptionModal({
     HydratedBodyRangesType | undefined
   >();
 
-  const [isScrolledTop, setIsScrolledTop] = React.useState(true);
-  const [isScrolledBottom, setIsScrolledBottom] = React.useState(true);
+  const [scrolled, setScrolled] = React.useState(false);
+  // We don't know that this is true, but it most likely is
+  const [scrolledToBottom, setScrolledToBottom] = React.useState(true);
 
   const scrollerRef = React.useRef<HTMLDivElement>(null);
 
@@ -47,17 +49,10 @@ export function AddCaptionModal({
   const updateScrollState = React.useCallback(() => {
     const scrollerEl = scrollerRef.current;
     if (scrollerEl) {
-      setIsScrolledTop(scrollerEl.scrollTop === 0);
-      setIsScrolledBottom(
-        scrollerEl.scrollHeight - scrollerEl.scrollTop ===
-          scrollerEl.clientHeight
-      );
+      setScrolled(isScrolled(scrollerEl));
+      setScrolledToBottom(isScrolledToBottom(scrollerEl));
     }
-  }, [scrollerRef]);
-
-  useEffect(() => {
-    updateScrollState();
-  }, [updateScrollState]);
+  }, []);
 
   const handleSubmit = React.useCallback(() => {
     onSubmit(messageText, bodyRanges);
@@ -68,8 +63,8 @@ export function AddCaptionModal({
       i18n={i18n}
       modalName="AddCaptionModal"
       hasXButton
-      hasHeaderDivider={!isScrolledTop}
-      hasFooterDivider={!isScrolledBottom}
+      hasHeaderDivider={scrolled}
+      hasFooterDivider={!scrolledToBottom}
       moduleClassName="AddCaptionModal"
       padded={false}
       title={i18n('icu:AddCaptionModal__title')}

ts/components/Modal.tsx

@@ -18,6 +18,7 @@ import * as log from '../logging/log';
 import {
   isOverflowing,
   isScrolled,
+  isScrolledToBottom,
   useScrollObserver,
 } from '../hooks/useSizeObserver';
 
@@ -175,6 +176,7 @@ export function ModalPage({
   const bodyInnerRef = useRef<HTMLDivElement>(null);
 
   const [scrolled, setScrolled] = useState(false);
+  const [scrolledToBottom, setScrolledToBottom] = useState(false);
   const [hasOverflow, setHasOverflow] = useState(false);
 
   const hasHeader = Boolean(hasXButton || title || onBackButtonClick);
@@ -182,6 +184,7 @@ export function ModalPage({
 
   useScrollObserver(bodyRef, bodyInnerRef, scroll => {
     setScrolled(isScrolled(scroll));
+    setScrolledToBottom(isScrolledToBottom(scroll));
     setHasOverflow(isOverflowing(scroll));
   });
 
@@ -250,6 +253,7 @@ export function ModalPage({
           className={classNames(
             getClassName('__body'),
             scrolled ? getClassName('__body--scrolled') : null,
+            scrolledToBottom ? getClassName('__body--scrolledToBottom') : null,
             hasOverflow || scrolled ? getClassName('__body--overflow') : null
           )}
           ref={bodyRef}

ts/hooks/useSizeObserver.tsx

@@ -93,11 +93,10 @@ export function SizeObserver({
   return children(ref, size);
 }
 
-export type Scroll = Readonly<{
-  scrollTop: number;
-  scrollHeight: number;
-  clientHeight: number;
-}>;
+// Note: You should just be able to pass an element into utils if you want.
+export type Scroll = Readonly<
+  Pick<Element, 'scrollTop' | 'scrollHeight' | 'clientHeight'>
+>;
 
 export type ScrollChangeHandler = (scroll: Scroll) => void;