I saw that the team just dropped this in beta a few hours ago: The melody editor has arrived!
You can find the new melody editor in the Music drawer of the toolbox. I love how brilliantly simple the block is. The melody player blocks until the melody has finished playing, so you can string multiple melody blocks together to create longer songs.
To add background music to a game, add melody blocks to a
Kudos to the team for a great addition!
Note: The comments above on how the block works are not my own. I totally stole them from Kim’s comments in GitHub. Kim is the primary author of the melody block. See the full set of comments here, complete with screenshots: