MySQL Workbench Administrator - GUI "Access denied for user root " gotcha

Here is a small newbie problem I found and resolved. The behavior of the GUI is a little confusing so I figure I will share. Running some Java examples, I have MySQL set up on Windows. After making a little progress I ran into a problem with a sample database JDBC connection. I wanted to look at that database connection's admin user info in the Workbench to see what's going on. So I click "Users and Privileges" - the gui pops up a message: "Access denied for user 'root'@'localhost' (using password: YES)" - what? I know the root password, set it myself. There was no opportunity to enter it in the GUI just now, only a rude popup. So I went hunting for some tip on how to update a config file for the GUI to read the root password.