Based on https://github.com/ysc3839/AudioPlaybackConnector, improved tray icon color - green when connected, and red when disconnected.
To make it work, you need to change the BT device address to what you want. https://github.com/hmkim123/AudioPlaybackConnector/commit/6d83f3e4d04a979c4846ce7129c02dc8e7e7b2e7#diff-04b0d548dcf888b3c84ee9703f7f87921c6a52a45d3d92d59a9e533559dd3380R476