fltk 1.3.28

//!A counter using messaging over a channel.
//!
//!The code can be found in the `examples` directory next to the `src` directory in the source distribution.
//!### Description
//!Contains a button for increment and decrement each. It uses messaging over a
//![`channel`](crate::app::channel) via
//![`Button::emit`](crate::prelude::WidgetExt::emit).