Any way to prevent custom search engines from replacing spaces with pluses?

SALZKARTOFFEEEL

SALZKARTOFFEEEL

When creating a new custom search engine you will have to put the search URL with a %s wich will be replaced with the entered search string. However, it is not replaced literally, every space is replaced with a plus sign (and any meaningful characters in URLs will be escaped using a percent sign).

While the escaping of special characters is very useful and not limiting at all, the replacement of spaces with pluses is very annoying to me! Popular search engines like Google deal with this correctly and later replace the plus sign with a space again, but when adding the Microsoft Developer Network, for example, as a search engine any search with more than one word will not get the result you want, since MSDN treats pluses literally.
For MSDN to work properly, the space should just be escaped like any other character (with %20 in this case)
(Here is the search string for testing: "/social.msdn.microsoft.com/Search/en-us/?query=%s")

Now, is there already a way to handle this? maybe with the "POST-Query String"? (I honestly have no idea what POST is.) If so, please tell me. Even any sort of Java Script that I can bodge into the search query that replaces spaces with %20 would be enough.
If there is currently no way to do this correctly, this would be a feature request for new versions of Opera as well.
Also, this is my first time posting, so tell me if I'm on the wrong forum, sub-forum, etc., or if this is not even an error related to Opera at all (maybe this has more to do with the chromium engine Opera uses).