Are you closing it using the macOS X button?
Unfortunately BTT gets no notification if that is pressed, thus can't react to it and still thinks the bar is visible.
(code buttonns :s yeah I could tell, but they really need refinement! the + is kinda off-centre and the square is a bit off. I think changing them to image buttons would be better in the long run but well, go at your own pace
I'll probably do the device icons next based on their emojis)
Yup, I'm currently migrating all the various old settings to the new UI technologies. After that is done (in a few hours) all the basic things are complete. Then there will probably be a first public preview release followed by many refinements based on new and existing feedback
Device icons are a lot of work! Not sure if it's worth it to recreate them, but feel free to