diff --git a/app/block_view.rb b/app/block_view.rb
index ba89dbb..910ac42 100644
--- a/app/block_view.rb
+++ b/app/block_view.rb
@@ -6,17 +6,27 @@ class BlockView
   include React::Component
   required_param :interpreter
 
+  before_mount do
+    interpreter.register_event(event: :block_changed, listener: self, callback: :block_changed)
+  end
+
+  def block_changed block
+    block! block
+  end
 
   def render
     div.row  do
-      div.col_md_6 do
+      div.col_md_5 do
         SourceView  :source => interpreter.block.codes.first.source
       end
-      div.col_md_6 do
+      div.col_md_5 do
         interpreter.block.codes.each do |code|
           code.to_s.br
         end
       end
+      div.col_md_2 do
+        button.btn.btn_default { "next" }.on(:click) { interpreter.tick }
+      end
     end
   end
 end
diff --git a/lib/eventable.rb b/lib/eventable.rb
index 6f632ac..a727430 100644
--- a/lib/eventable.rb
+++ b/lib/eventable.rb
@@ -3,17 +3,19 @@
 module Eventable
 
   # Register a handler for the given event name.
+  # The event name is the method name called on the handler object
   #
-  #   obj.on(:foo) { puts "foo was called" }
+  #   obj.on(:foo , some_object_that_implements foo( whateverargs)
   #
   # @param [String, Symbol] name event name
+  # @param [Object] object handling the event, ie implement the function name
   # @return handler
-  def on(name, &handler)
+  def register_event(name, handler)
     event_table[name] << handler
     handler
   end
 
-  def off(name, handler)
+  def unregister_event(name, handler)
     event_table[name].delete handler
   end
 
@@ -30,6 +32,6 @@ module Eventable
   #
   # @param [String, Symbol] name event name to trigger
   def trigger(name, *args)
-    event_table[name].each { |handler| handler.call(*args) }
+    event_table[name].each { |handler| handler.send( name.to_sym , *args) }
   end
 end
diff --git a/lib/interpreter.rb b/lib/interpreter.rb
index d9e32c0..3dcbf6f 100644
--- a/lib/interpreter.rb
+++ b/lib/interpreter.rb
@@ -17,18 +17,26 @@ class Interpreter
   end
   def set_block block
     return if @block == block
+    old = @block
     @block = block
-    trigger(:block, block)
-    set_instruction block.codes.first
+     trigger(:block_changed , old , block)
+     set_instruction block.codes.first
   end
   def set_instruction i
     return if @instruction == i
+    old = @instruction
     @instruction = i
-    trigger(:instruction, i)
+    trigger(:instruction_changed, old , i)
   end
   def tick
     name = @instruction.class.name.split("::").last
-    send "execute_#{name}"
+    fetch = send "execute_#{name}"
+    return unless fetch
+    get_next_intruction
   end
 
+  def execute_Branch
+    target = @instruction.to
+    set_block target
+  end
 end