Code review comment for lp:~widelands-dev/widelands/bug-1825932-open-games

This will still leave us with a grey button and no color change in the editbox - rather than spending a lot of time on hacking workarounds, let's wait for https://code.launchpad.net/~widelands-dev/widelands/font_size-lua/+merge/366938 so that we can change the text color. It will be really easy to implement then.

The rest of the changes look good :)