Collision is the tool that determines whether or not items will overlap in the Spaces Flex design environment, meaning it defines whether an object can pass through another or not.
To enable or disable collision for an item, select the desired object and click on the indicated icon :
Collision Modes in Spaces Flex
Active Collision: When an item's collision is active, that item's movement through the environment is restricted to free space. As you move the object, it will "brake" when it encounters another item, causing a collision.
Collision Disabled: When collision is disabled, the item can move freely in all directions, even overlapping objects in its path.