How can I add my own button to textarea

Hey,
how can I add my own button to the standard textarea?
I need a center- button.

What have I to do to extend a coreplugin in K3?

Best

Not particularly a button, but that should do the trick:

Hi,
a center KT to develop is not the problem.
I have written my own kirbytag but what I need is a Button in the toolbar for my customer.
But thanks for the link.

Cheers

You might be able to find a starting point by looking at existing field extensions, for example: https://github.com/mullema/k3-date-format