Admin markdown form field

Hi,

I'm new to Grav, but loving it so far!

I've managed to add some custom fields to my admin interface via blueprints, which is fantastic. I do however have one question...

One of the custom fields I'm trying to add is a markdown text box. I've managed to get it to display in my custom tab, but it only takes a single paragraph. As soon as I add a line break, the validation fails.

I've scoured the docs to see what settings are available, but the markdown form field is not mentioned. In fact, I only knew it existed because I found it here:
https://github.com/getgrav/grav-plugin-admin/tree/master/themes/grav/templates/forms/fields

I've tried random settings like:

multiline: true
preview: true (I would like to enable the preview mode)

But neither of them work;(

Any help would be greatly appreciated.

I would also like to know the answer to this, but I found a solution anyway by looking in the file system and it looks like adding a validation in your blueprint make it works, example:

header.myblogtext:
              type: markdown
              validate:
                type: textarea

Not sure if it change something, but I have the option 'auto line break' in Configuration>System toggled to 'Yes'.
Hope it helps!

Thanks @paulmassendari, that validation option did the trick.