Bug 511191

SUMMARY
I delete numerous notifications from a bot in a Matrix room regularly. But it appears to do nothing. The window does not show the messages disappearing, there is no spinner to show that something is happening or a progress bar if it knew how many messages it was trying to delete.

STEPS TO REPRODUCE
1. Go into a room with numerous messages from another user account (or yourself in some testing room)
2. Click on the user account and select delete all messages

OBSERVED RESULT
Nothing appears to be happening

EXPECTED RESULT
Some indication that there is activity happening.

Other Notes:
- The whole process to delete messages takes roughly 1 minute.
- The Element web interface shows how many messages will be deleted (as it doesn't delete ALL messages from the user). I assume this issue is some restriction on the server side, as the client is requesting deletion of only messages it knows about (in the client DB/buffer) and the server doesn't support deleting all messages by a user.