Can I change the font of onboard?

When I am typing with font of other language (not actually cahnge in language-source or input-method but this is font only), I want to show layout of keyboard according to that font. I've used onboard in order to use as on-screen keyboard but I can't find any setting related to change font.

So, How do I cahnge font of onboard?

OR, help me to find out : Is there any free-software on-screen keyboard available with feature of changing font?