"Also, since most System Tray icons are applets which hardly ever handle any files."
You forgot about applications like Telegram, Skype, etc. These applications indeed accept files for sending. Currently if I want to send a file via drag and drop I have to open the window (e.g. Telegram) first (if it is minimized to the system tray), then I can drag and drop it. Wouldn't it be more convenient for the user to have DnD support in the system tray? I think Apple has exactly this feature. Best regards, Martin
