I am not sure how you're setting the current language, but when you go to www.domain2.com/en, the Thread.CurrentThread.CurrentUICulture value should be en-GB and  umbraco.library.Session("lang") should be "en".

Is it like this?

No, this is what I get in Page_Load

Domains (umbraco.library.GetCurrentDomains(node.Id);)
Name: www.domain2.com/en/
Language name: English (United Kingdom)
Language id: 3
Language alias: en-GB

Session lang:

Thread lang:da-DK

If I take a look at the umbdebugshowtrace, the last line in pre-init says
default.aspx    Culture changed to da-DK

I think it doesn't change the session language.

I don't know how you implemented the multilanguage functionality, so I tell you how I did it. Maybe it helps.

In the page load event of every page ( in the main master page) :

1. I get the language from the query string ( I also have domain/language and I use UrlRewriting to set the query string value for language - if you're not using any rewriting, you can parse the url)

2. I call a function that sets the current language and mainly does this:

        Thread.CurrentThread.CurrentUICulture = currentCulture; //currentCulture = the culture corresponding to the language from the query string

        umbraco.library.setSession("lang", currentCulture.TwoLetterISOLanguageName);

If you do this from an xslt (it's an example I've found online), create a template that calls this function call it in the head of the main master page.

I hope it helps and that I explained well.

That seems like quite a workaround for something that ought to just work.

I've taken a look at the umbraco source code and to me the following code seems to be the problem. It's in page.cs in \umbraco\presentation

public string GetCulture()
        {
            if (Domain.Exists(HttpContext.Current.Request.ServerVariables["SERVER_NAME"]))
            {
                Domain d = Domain.GetDomain(HttpContext.Current.Request.ServerVariables["SERVER_NAME"]);
                return d.Language.CultureAlias;
            }
            else
            {
                for (int i = splitpath.Length - 1; i > 0; i--)
                {
                    if (Domain.GetDomainsById(int.Parse(splitpath[i])).Length > 0)
                    {
                        return Domain.GetDomainsById(int.Parse(splitpath[i]))[0].Language.CultureAlias;
                    }
                }
            }
            return "";
        }

If you take a llok at that it first checks to see if the hostnames contains the current ServerVariables["SERVER_NAME"]. Because of this check my culture will always be set to da-DK in this example and makes it almost impossible to use directory based hostname setup. Seems like a bug to me?

It does seem like a bug.

The multilingual site that I created has a different structure. I didn't want 2 different domains, so the document types had properties for each language. This was it was easier to get the same page in each language.

What I did see is that those 2 (Thread.CurrentThread.CurrentUICulture and Session("lang") have to be set correctly to get the correct dictionary items.

Sorry I can't help you more with this.

Please go and vote: http://umbraco.codeplex.com/workitem/23342

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