It might make more sense for window controls to also be status applets, since not all windows can be minimized, maximized, or closed. For instance, if a particular window is no longer needed and only showing some completed action, the close button could turn green. If there's an error, it could turn red. If a process could take a long time, a progress bar could appear and the minimize button could turn green. If a web browser could show a web page better with fullscreen, the maximize button could turn blue. This would follow the applet colour coding scheme.
One could even add some custom window commands (such as resize to content) to their applications.
>since not all windows can be minimized, maximized, or closed.
This is one of the worst usability problems on the desktop. Granted, it doesn't show up in the "default configuration" but do a little thing like change the text size and that dialog box that won't let you resize suddenly is completely broken.
Though I suppose this is part of a bigger problem, that changing fonts is by design a "power user" feature.
It would only work in a 'Mac World' where there was a set of interface guidelines that were not only religiously followed by developers, but also rigorously requested by users.
One could even add some custom window commands (such as resize to content) to their applications.