I do not see a reason why tray icon has to be a plugin. Small pieces of code like this can easily be integrated into the program engine. You can later edit the INI settings to disable parts of the program you do not wish to load. I like the GUI plugin idea for it allows users to make their own GUIs that way. The console window needs to be part of the engine in either case, but users can still choose not to display it on startup (can access it later via system tray icon).