Postback messages create empty space

[v-kydela]

Version

4.9.0

Describe the bug

When the user sends a textless message (as when clicking on a postBack button) the Emulator pads the transcript with an invisible element. This is especially noticeable when the bot does not reply to that textless mesage, so the invisible elements can accumulate.

To Reproduce

1. Start a conversation with a bot that uses postBack buttons
2. Click on a postBack button
3. Observe

Expected behavior

Invisible messages should not take up space. They don't in any other channel, including Web Chat.

Screenshots

Additional context

Rather than being used as placeholders for the textless messages themselves, the invisible elements seem to be placeholders for the "Restart conversation from here" buttons. The Emulator seems to allocate space for those buttons under every user-to-bot message regardless of whether those messages take up space on their own. One might think that this is necessary, but the "Restart conversation from here" buttons could still be accessed by clicking on the activity in the log panel.

[bug]

[tonyanziano]

I think this also happens for conversation updates.