on_refresh

The on_refresh method defines callback behavior that is triggered when a Window is refreshed. It generates a CrystGLFW::Event::WindowRefresh that is yielded to the block:

window = Window.new

window.on_refresh do |event|
  puts "window refreshed!"
end

With this callback defined, every time window is refreshed, it prints "window refreshed!" to standard output.

on_refresh must be called from within a run block definition.