Add down arrow for ListBox

lib/cyberarm_engine/ui/elements/list_box.rb

@@ -31,6 +31,13 @@ module CyberarmEngine
         self.choose = @choose
       end
 
+      def render
+        super
+
+        w = @text.textobject.text_width("▼")
+        @text.textobject.draw("▼", @x + content_width - w, @y + @style.padding_top, @z, 1, 1, @text.color)
+      end
+
       def choose=(item)
         valid = @items.detect { |i| i == item }
         raise "Invalid value '#{item}' for choose, valid options were: #{@items.map { |i| "#{i.inspect}" }.join(", ")}" unless valid