Number field with decimal numbers

Hi,
I am creating a travel diary for our world trip. I need number fields with decimal numbers like 19,88 for kilometers, prices, currencies, fuel consumption, costs.

I can set the increment to .1 but as soon as I try to enter a decimal value it says “not a valid number”. Clicking throught to ,67 is boring and makes no sense at all.

I think there is a bug in this field. It should accept decimals or it makes no sense at all.

If this is configrable, it is not in the handbook. Please tell me how to get a solution.