Thanks to Nicola for his support in all (many!) forums with qTranslate. And especial for this very useful plugin!
I have installed qTranslate with 2 lang (Ru|En). My site setup default to (Ru) lang with an option for second (En) like 'site.com/en/...'
Before this plugin when I press 'Post comment' from second non-default-lang (En) page I was switched to my default-lang (Ru) same page.
After some search find this plugin, installed and happy :)
Tested with 2-lang commenting - all work as must in both lang.
Funny was testing with mixed language comments (En+Ru) - page stay at same lang!
This is not bug - this is feature! (Это не баг - Это фича!)
Thanks again to Nicola!