ContainerProperties.ListDirection Property (Visio)
Determines the primary list direction of the container shapes. Read/write.
The value of the ListDirection property can be one of the following VisListDirection constants.
Shapes are arranged horizontally, from left to right.
Shapes are arranged horizontally, from right to left.
Shapes are arranged vertically, from top to bottom.
Shapes are arranged vertically, from bottom to top.
If the container is not a list, Microsoft Visio returns an Invalid Source error.