So the user loses nothing if that action is unavailable. However, selecting Play makes sense in this situation. And once Play has been executed, it now makes little sense to press Play once again, but it makes sense to press Stop. If this still isn't clear, have a look at the program. To enable one action, we simply have to show one member of the pair and hide the other member of the pair.
Most programmers are familiar with pushbuttons.
And that's how we'll implement most of the actions. We're not building a game here. That's why I used graphical buttons. Display Aside from issuing commands, an interface has to provide information to the user. Currently, the current track and one of four time display are provided.