getFirstItemInViewportIndex, getLastItemInViewportIndex, getItemOffset are not taking into account ConversationTagHeader items: they are rendered and taking height, but not considered when you counting unreadMentionIndices. That's why scroll to bottom, and computing when to show a button has slightly offset with tags used.
Originally posted by @Antreesy in #18036 (comment)
getFirstItemInViewportIndex,getLastItemInViewportIndex,getItemOffsetare not taking into account ConversationTagHeader items: they are rendered and taking height, but not considered when you counting unreadMentionIndices. That's why scroll to bottom, and computing when to show a button has slightly offset with tags used.Originally posted by @Antreesy in #18036 (comment)