Extending core blocks

[ryanwelcher]

Examples of how to extend/modify existing core blocks.

[dgwyer]

It would be great to also demonstrate how to extend core blocks without breaking existing instances of the block.

I've always been reluctant to extend core blocks for this reason so would like to know any tips for not affecting the block output that would result in the dreaded block markup validation error!

[AdamWills]

Something that I was looking into doing recently - using the existing columns block, but instead of of using their supplied classes/CSS, we wanted to use our site's existing grid system.

[ryanwelcher]

Setting the defaults for a core/table block