add the ability to preview messages, or a larger editor in the RHB
It would be really great to be able to have a preview of a message before it's sent. Putting a full-size, WYSIWYG-able editor available in the right-hand bar would make it easier to compose longer messages, especially if you need to reference other posts inside of Mattermost.
Paul Rothrock commented
Or there could be a UI element that expands the existing input field to allow multi-line formatting.