on_framebuffer_resize

The on_framebuffer_resize method defines callback behavior that is triggered when the frame buffer of a Window is resized. It generates a CrystGLFW::Event::WindowFramebufferResize that is yielded to the block:

window = Window.new

window.on_framebuffer_resize do |event|
  puts "window frame buffer resized to #{event.size}"
end

With this callback defined, every time window's framebuffer is resized, its new dimensions are printed to standard output.

on_framebuffer_resize must be called from within a run block definition.