Emoji reaction improvements

[dotmacro]

Problem

1. Sometimes when tapping "..." the "Add a reaction" (or the last item in that menu) above the compose box is hidden by the "Jump to latest message" link
   

2. When "..." is near the top of the visible chat history, tapping it merely makes it disappear rather than opening any menu or tooltip, or causing anything else to happen on the page.

Solution

1. Whatever menu the user might open should never be hidden by automatic "jump to latest message" link.
2. If "..." is visible, it should be tappable/usable. If it's not tappable/usable, it should not be visible.