Change decimal mark in calculator

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http://askubuntu.com – In Germany we use , as decimal mark instead of .. Since I installed my Ubuntu in English, the Ubuntu default calculator (gcalctool) uses the . and I can't use the , on my German numpad. I already set up German in System Settings...=>Language Support=>Regional Formats but it doesn't seem to set it for the calculator. I also saw this question but I want to avoid remapping my keys. Can someone tell me if and how I can change this for the calculator or recommend a calculator that supports it? (HowTos)