on_cursor_cross_threshold

The on_cursor_cross_threshold method defines callback behavior that is triggered when the system cursor either enters or exits a Window. It generates a CrystGLFW::Event::WindowCursorCrossThreshold that is yielded to the block:

window = Window.new

window.on_cursor_cross_threshold do |event|
  if event.entered?
    puts "cursor entered window"
  else
    puts "cursor exited window"
  end
end

With this callback defined, every time the cursor enters or exits window, the appropriate message is printed to standard output.

on_cursor_cross_threshold must be called from within a run block definition.