Decimal separator Please Help

I have just ported an application written in Informix 4GL from UNISYS machine to a DELL PC with Red Hat Linux V6.1, Informix SE V7.2 and Informix 4GL Compiler V7.2 installed. I am running into a problem with both PC keyboard and dumb terminal's, that's, in an input form, when I type the "." symbol at the keypad, we get "." not "," as before since we use French language and "," as decimal separator. As I am new to Linux and Informix world, I have no idea where I should change something, in Linux, or Informix SE, or Informix 4GL, or the application? In Windows, I can set the decimal separator at operating system level, then software like Excel will take it as decimal separator and convert "." into "," when I strike "." key at keypad. By the way, I set the Informix environment DBMONEY to ",", but it does not help. Also I tried to use GLS by setting CLIENT_LOCALE, DB_LOCALE and SERVER_LOCALE to French locale, but it didnot work neither. Any idea is greatly appreciated. I am stuck! Thanks! Franck