PlacementLocation.Constant
You can specify three types of constants:
PlacementLocationBottom
The value for this constant is 3. Align the add-in control under the design window.
PlacementLocationLeft
The value for this constant is 0. Align the add-in control to the left of the design window.
PlacementLocationRight
The value for this constant is 2. Align the add-in control to the right of the design window.
PlacementLocationTop
The value for this constant is 1. Align the add-in control above the design window.