Hey!
Everything looks fine. Just one thing - when dropdown is opened, the cursor is below it.
P.S. I do understand correctly, that the only way to test it with Trello is by building an actual build, right? Surely.

Hello! 

Just one thing - when dropdown is opened, the cursor is below it.

This is the first time I've heard of issues with the cursor appearing below UI elements. If you are using the system cursor I didn't even think that would be possible. Are you using some kind of custom solution (i.e. a cursor image in the UI) for your cursor? Also, what version of Unity and what platform?

P.S. I do understand correctly, that the only way to test it with Trello is by building an actual build, right?

If you've already configured EF and connected it to Trello, you should be able to submit to Trello from either the editor or a build. Our team submits from the editor all the time to keep track of bugs as we're working.