Tray icons are a pretty uncommon feature in GUI apps. You will probably have to call the OS apis directly. I would look at the win32 API docs: https://learn.microsoft.com/en-us/windows/win32/api/shellapi/nf-shellapi-shell_notifyiconw and examples and how we do that in windy: https://github.com/treeform/windy/blob/master/src/windy/platforms/win32/platform.nim#L1278-L1350
Its not simple I did ask chatGPT and it produced even more code: https://chat.openai.com/share/52b5c304-20b9-495a-8d9e-534b2d79771d
I hope that helps.