Hi JURAJ
How are you, i'm working with David.
seem to have no effect on the cache control......
Our problem is a the output cache level. do you have a solution to exclude from the cache the query string ? 
The following scenario produce ou bug : 
1)	I have a page “test” with nothing but a "language selection with flags" web part.
2)	I access this page for the 1st time, with parameters. Ex: http://example/en-CA/test?abc=123&edf=456.
3)	I access the same page on another browser (or another system) but without the parameters. http://example/en-CA/test
4)	I switch language on the other browser. The URL becomes http://example/fr-CA/test?abc=123&edf=456 These parameters should not be transferred from one session to another. Only the language should change.
The following scenario WORK normally : 
1)	I have a page “test” with nothing but a "language selection with flags" web part.
2)	I access this page for the 1st time, with parameters. Ex: http://example/en-CA/test?abc=123&edf=456.
3) 	I CLEAR THE KENTICO CACHE 
3)	I access the same page on another browser (or another system) but without the parameters. http://example/en-CA/test
4)	Kentico Keep the URL clean : http://example/en-CA/test and doe not add the previous query string