Changing Between Different Opacities

[Culex]

I have an option menu that changes between different opacities (let's say 200 for transparent and 255 for opaque). How can I make a certain number the defining number for the system's opacity? I'm hoping that makes sense.

Here's what I've tried:

I added an attr_accessor in Game_System and then went below into the def initialize method and added @window_opacity = 255. Then I had this in my Scene_Option script:

[...]
case @opacity_window.index
      when 0  # Transparent
        $game_system.se_play($data_system.decision_se)
        $game_system.window_opacity = 200 # For transparent
        @dummy_window.opacity = 200 # To change the current scene's window opacity
      when 1  # Opaque
        $game_system.se_play($data_system.decision_se)
        $game_system.window_opacity = 255 # For opaque
        @dummy_window.opacity = 255 # To change the current scene's window opacity
      end
[...]

However, when I select a command it comes up with an error about "integer conversion implicity" or something like that. So obviously I'm going about this wrong.

Help is appreciated and credit is given where credit is due, of course. ^_^

 

[Daniel]

What line does the error appear on, if any?