Glimmer DSL for LibUI (Prerequisite-Free Ruby Desktop Development Cross-Platform Native GUI Library) version 0.12.0 ships with an exciting new feature called Custom Control Component Slots!!! Component Slots are containers that could accept content in different parts of a Custom Control component (e.g. an address_form Custom Control can have a header slot and a footer slot to display extra information about the address being entered, which consumers could fill in with any GUI controls). A new example has been implemented to demonstrate this feature: Class-Based Custom Control Slots.