Handle an Events. Returns non-zero if the widget understood and used the event.
The default version returns true for fltk::ENTER and fltk::MOVE events, this is done so you can put tooltips on the base widget. All other events return zero.
Information on how to write your own version of handle() is can be found under Events.
If you want to send an event to a widget you probably want to call send(), not handle(). Send will do extra work with each event before calling this, such as turning HIGHLIGHT and FOCUSED flags on/off.
Reimplemented in fltk::Divider, fltk::Group, fltk::Window, fltk::DockWindow, fltk::ToolWindow, and fltk::WindowHolder.