If you go to https://phabricator.wikimedia.org/calendar/query/month/ - you can see that event names have only two letters displayed. Which would be fine if tooltip showed the full name, but it also doesn't. So to know what event is I have to click through on each one and read the description. It would be nice to at least have the tooltip display the actual event name.
Upstream: https://we.phorge.it/T15477