Extending core blocks

[Messa]

Hello.

Do I miss there something?
I want to use the image block element and want to add there two checkboxes.
And I see the new checkboxes but no HTML output in the frontend.

I also copied the template “image.php” im my block template folder. But nothing on the frontend

layout:
        label: Layout
        type: fields
        fields:
          layout:
            type: layout
            layouts:
              - "1/1"
              - "1/2, 1/2"
              - "1/3, 1/3, 1/3"
            fieldsets:
              - heading
              - text
              - extends: blocks/image
                fields:
                  fullwidth:
                    label: volle Breite
                    type: checkboxes
                    options:
                      - Ja
                  background:
                    label: Blauer Balken
                    type: checkboxes
                    options:
                      - Ja

[texnixe]

Overview

[Messa]

Thank’s fount now the right way.

      fieldsets:
        - heading
        - text
        image:
          extends: blocks/image
          fields:
            fullwidth:
              label: volle Breite
              width: 1/2
              type: toggle
            background:
              label: Blauer Balken
              width: 1/2
              type: toggle