Many FlowParts, such as subroutines and loops, can contain code of their own. After creating such a container, FlowParts can be added by either dragging or dropping them into the container. The container will be highlighted to indicate that it will become the new parent of the FlowPart.

The container takes responsibility for FlowParts nestled inside. If the expand button is unclicked, all contained FlowParts will be hidden - and likewise, the contents will be shown when the expand button is clicked again. Connections cannot be made between FlowParts in different containers, and the contents of a container will be moved about along with the container.