We're working hard on impoving Page Builder - making it the most powerful and flexible page building plugin for WordPress. If you'd like to help us with code contributions, here are a few ways you can help.
There are 2 main categories of we'd love to see from developers out there. These are bug fixes and additional hooks/filters. If you ever find a bug, you can either create a new issue, or submit a pull request to the Page Builder GitHub repo.
The same goes for additional hooks and filters. If you're working on a theme and plugin and you need a way to hook into Page Builder to customize its behaviour, either let us know or submit a pull request with the extra hooks.
We're trying to keep the core of Page Builder as light as possible. This makes it easier to update and maintain for a large audience. If you'd like to create a new feature for Page Builder, we suggest you create it as a plugin.
Some examples are implementing support for other grid systems like Bootstrap, or adding extra row/widget styles. Both are possible with some creative use of the existing hooks in Page Builder. You can see default-styles.php for an idea of how we've implemented styles in Page Builder.
If your plugin proves very popular and you give us premission, we'll integrate the new features into the core of Page Builder.
Our developer documentation is hosted on Github, so you can edit it with pull requests. Helping us improve our developer documentation is a great way to help out other developers build for Page Builder.