on_close

The on_close method defines callback behavior that is triggered when a Window is closed/destroyed. It generates a CrystGLFW::Event::WindowClose that is yielded to the block:

window = Window.new

window.on_close do |event|
  puts "Bye!"
end

With this callback defined, when the window is closed, it will print "Bye!" to standard output.

on_close must be called from within a run block definition.