Any blocks that are available in Drupal core's block administration form are also available as drag and drop components in any Glazed Builder instance. Add any dynamic content to your drag and drop builder and it simply works.
User Login Block
In Glazed Builder you can load any block in your drag and drop container. Here is an example of loading the user login form, but really you could load any form that is available as a block. Got a from from webform module you want to include? Just expose it as a block from the webform edit page.