custom BB code doesn't get the letter case of the tag right

[dimitrisvb]

I have some custom BB code where the tag is the greek letter delta: δ

Only, when i click on the button, the capital letter delta (Δ) is inserted instead.

On top of that, the tag will only work with the lower case δ

a) Is there a way that the lower case letter gets inserted?

b) Is there a way to have both δ and Δ work for this code?

thanks