Flip the display buffers

The implementation varies per platform.

Property definitions

gamnit $ GamnitDisplay :: flip
	# Flip the display buffers
	#
	# The implementation varies per platform.
	fun flip do end
lib/gamnit/display.nit:67,2--70,16

gamnit :: egl $ GamnitDisplay :: flip
	redef fun flip
	do
		assert glGetError == gl_NO_ERROR

		assert egl_display.is_valid

		egl_display.swap_buffers(window_surface)
	end
lib/gamnit/egl.nit:156,2--163,4