Can't input chinese in fox gui?

hi ,everyone,i made a gui with fxruby,there is a problem, can’t input
chinese in the fox gui ,how to solve the problem?

there is an simple program,

require ‘rubygems’
require ‘fox16’
require ‘jcode’
$KCODE = ‘u’
include Fox
application = FXApp.new(“测试”, “测试”)
main = FXMainWindow.new(application, “Hello”, nil, nil, DECOR_ALL)
FXButton.new(main, “&测试, 测试!”, nil, application, FXApp::ID_QUIT)
application.create()
main.show(PLACEMENT_SCREEN)
application.run()

测试 is the meaning of “test”,
when i run the program, an output :
Warning: $KCODE is NONE.

chinese character can’t display on the window,there are many boxes on
the window!

what’s the matter?