APEX

Hi all,
please, could anybody help me with following problems? In Czech locale we have decimal separator "," and thousand separator " ", but unfortunately when I set primary language in Globalization attributes

Application Primary Language Czech (cs)
Application Language Derived From Application primary language

I have thousand separator ".".

Debug window says:

0.43800 0.00000 alter session set nls_language="CZECH" 3
0.43800 0.00000 alter session set nls_territory="CZECH REPUBLIC" 3
0.43800 0.00000 NLS: CSV charset=EE8MSWIN1250 3
0.43800 0.00000 ...NLS: Set Decimal separator="," 3
0.43800 0.00000 ...NLS: Set NLS Group separator="."

How can I set thousand separator properly for the whole application?
I tried to make a little "workaround" - I created following application process, that is run Before header

BEGIN
EXECUTE IMMEDIATE 'alter session set NLS_NUMERIC_CHARACTERS = '', '' ';
END;

and numbers are shown correctly, but if I set any filter on a report, correct number formatting is gone and thousand separator is again "." until I click the "refresh page" button (after that numbers are again formatted correctly till I add something else to the filter).

Another problem is with a built-in calculator (item type Text field with calculator popup), that propagates "." as a decimal point into the text field instead of "," (according to my locale settings). So if I submit the page then, I get "numeric or value error: character to number conversion error".
Thanks in advance,
Pavel