Is the cursor locked et the center of the screen?

Property definitions

gamnit $ GamnitDisplay :: lock_cursor
	# Is the cursor locked et the center of the screen?
	var lock_cursor = false is writable
lib/gamnit/display.nit:40,2--41,36

gamnit :: display_linux $ GamnitDisplay :: lock_cursor
	redef fun lock_cursor do return sdl.relative_mouse_mode
lib/gamnit/display_linux.nit:41,2--56