Some days I spend 2 hours chasing red herrings (like "perhaps my JSON ajax
calls arn't running asynchronoously?") that turn out to be a simple
one-word typo. This was one of them.

However, I did get the sidebar displaying alert messages, which can be
easily sent to the user from any part of the assistant. This includes
transient alerts of things it's doing, which disappear once the action
finishes, and long-term alerts that are displayed until the user closes
them. It even supports rendering arbitrary Yesod widgets as alerts, so
they can also be used for asking questions, etc.

Time for a screencast!

<video controls src="http://joeyh.name/screencasts/git-annex-webapp.ogg"></video>
