Chat preview content cannot be scrolled, allowing incriminating content to be inserted outside of the visible window

The bug

Because MC-254401 is working as intended, the chat preview field is not limited in size. However, this means that it is possible for some of its content to extend past the edge of the client window. A server can use this to hide incriminating content that is not visible to the player when sending their message.

How to reproduce

1. Paste the command:

   /say You are a INSERT_SLUR_HERE. @e @e

   INSERT_SLUR_HERE is not visible in the chat preview

Although in this example, the player types INSERT_SLUR_HERE, the server could modify the message to include this content without the player knowing.