Fix major incorrect usage of mrb class definitions causing segfaults

samples/button.rb

@@ -1,8 +1,14 @@
-App.run 400, 400, "Button Test"
+App.run 720, 480, "Button Test"
 
 main_scene = Scene.new
+
 default_font = Font.new "assets/fonts/charybdis.ttf", 24, pixel_art: true
 
+bg_image1 = Image.new "assets/images/menu_bg.png", alpha: 0.7, pixel_art: true
+bg_image2 = Image.new "assets/images/game_over_dead_bg.png", alpha: 1, pixel_art: true
+
+bg_animation = Animation.new [bg_image1, bg_image2], fps: 5
+
 App.language = :en
 App.localize(:en, :btn_text, "Click me!")
 
@@ -10,6 +16,8 @@ text = ElementText.new :btn_text, default_font, position: {x: 50, y: 50}, z: 1,
 
 rect = ElementRect.new({x: 50, y: 50, w: 100, h: 25}, 0xFF0000FF, z: 0)
 
+image_element = ElementImage.new bg_animation, position: {x: 0, y: 0}, z: -1
+
 rect.on_click do
   rect.color = rect.color == 0xFF0000FF ?
     0x00FF00FF
@@ -17,14 +25,15 @@ rect.on_click do
     0xFF0000FF
 end
 
-=begin
-main_scene.update do |dt|
-  puts "Delta time: #{dt}ms"
+main_scene.on_update do |delta_time|
+  # puts "Delta time: #{delta_time}ms"
+  # commented out to avoid spamming the console, but you can uncomment to see the delta time being printed every frame
+  # runs at 60fps, so you should see around 16-17ms being printed
 end
-=end
 
 main_scene << text
 main_scene << rect
+main_scene << image_element
 
 # main_scene.delete(text) # Uncomment to test element deletion