Colored borders

[chnoack]

Hi,
thanks a lot for this awesome piece of software. I am impressed by command line tools like "lazygit" and started migrating my own invoicing software from Ruby on Rails to Elixir at first with a terminal UI.
Ratatouille comes in handy here. There is one thing I'm missing (maybe it's there and I did not see it ): it would be great to have a color option for the borders of a panel.
With this option you could have "active" panels like in lazygit or lazydocker.
I tried to add the color to the panel borders, but could find out how to get them from the panel call to the rendering.

Best regards,

Christian