Trouble using when two UFOs are open

[traviskochel]

Seems like a handy tool! I was trying this out on a two source family, but found an issue when trying to add a designspace file to the second UFO. It keeps trying to open the designspaces modal on the UFO that was opened first, with no way to edit the second. Here's the simplest way to recreate:

1. Create two new UFO files
2. On the second UFO, click 'designspaces' buton
3. It switches back to the first UFO, and opens that modal
4. Closing the first UFO and clicking the design spaces button then results in the error below, in the output window
5. With existing UFOs, the only want to edit is to restart Robofont and open the second UFO first