Add more flexible theme support (e.g. disable-custom-colors and disable-custom-font-sizes)

I would like to second this request. This is a must have for any site where website governance and enforced style standards are important . I cannot use this module on a production site without these sorts of controls. Ideally, they could be connected to Drupal permissions, but it would also be great if text sizing and color options could just be switched off.

I would also love to see this. The above comments are right, you can't really use this is a customers production site without being able to customise these options.
As it is already available in the WordPress version, I would be surprised if its not already in the stable release somehow but just not documented.
If this is the case, some extra documentation on https://www.drupal.org/docs/8/modules/gutenberg/create-a-custom-palette-in-a-theme would be great.

I am adding a patch to allow for the gutenberg.yml file to be able to override some more of the editor options, specifically:

• disableCustomColors
• disableCustomFontSizes
• disablePostFormats (not really sure what this one does though)
• codeEditingEnabled
• gradients (Block Gradient Presets)
• fontSizes (this one already existed but was not documented)

You and then override these settings in your themes gutenberg.yml file (mytheme.gutenberg.yml) under `theme-support`.

E.G.

theme-support:
  colors:
    - slug: "black"
      name: "Black"
      color: "#000000"
    - slug: "white"
      name: "White"
      color: "#FFFFFF"
    - slug: "dark-midnight-blue"
      name: "Dark Midnight Blue"
      color: "#003366"
    - slug: "very-dark-orange"
      name: "Very Dark Orange"
      color: "#663300"

  gradients:
    - slug: 'vivid-green-cyan-to-vivid-cyan-blue'
      name: 'Light green cyan to vivid cyan blue'
      gradient: 'linear-gradient(135deg,rgba(0,208,132,1) 0%,rgba(6,147,227,1) 100%)'

  fontSizes:
    - name: "Small"
      size: 12
      slug: 'small'

  disableCustomColors: TRUE
  disableCustomFontSizes: TRUE
  disableCodeEditing: TRUE

The only thing I cant workout is when you enable disableCustomFontSizes, it removed the text field to input the custom size, but doesn't remove custom from the select list. If any one else can would that bit out, it would be greatly appreciated.

The patch applies to the current dev version.

This patch is for the current 8.x-1.10 release if anyone wanted to try it in a development environment.

Thanks codebymikey!
It took ages to get npm run build to work correctly as it wouldn't install from the package.json correctly fyi.

Attaching the patch to the es6 file.

Ah damn, sorry. I wasn't sure how the code was being built when packaged up to drupal.org. I assumed it might build it.

Ok, here is another patch for the es6 file and includes the generated gutenberg.js file.
I have also included the changes to the colors and the fontSizes constants to use the theme support variable.

I'm not really sure what you mean by that last bit as I'm a php dev really and not exactly the best at JS. I more figured this bit our by accident. I might leave that part up to someone else.