User-defined language not applying to specified file types in Notepad++

Question

I have created a fairly simple user-defined language in Notepad++, and given it an associated extension. But, when I open files I have named with that extension, nothing happens

Answer 1

This has been fixed, so I guess the whole question could be closed or deleted. I'm not sure in which version they fixed it, but in the latest v6.5.1 everything works as intended.

1. Go to menu Language > Define your language...
2. Create a new language or select from the dropdown menu an existing one
3. In the Ext. text box add your desired extension with no leading "." and space separated if you have multiple extensions.
4. Now open a file with such extension and it is properly highlighted. To confirm that the User Defined Language extension is correct, you can also take a look at the userDefineLang.xml usually stored in your %APPDATA%\Notepad++\ folder.