Import a file that creates a few databases.
At least if the import files with an error after succesfully creating some of the databases, then the database list/tree on the left panel is not completely updated. There are databases that have been created and don't show up there.
And what is worse, that list is never updated any more. If you go to the Databases tab, the list of databases displayed in the body of the page is complete and up to date, but still the one on the left panel is incomplete.
There's no refresh button or anything easy to find that will force it to refresh, besides the fact that you should never need that.