The Rotate option can be used to rotate a boundary. The Rotate option can be used with any boundary type in Slide.
To use Rotate:
Select Rotate from the Edit sub-menu of the Boundaries menu.
Use the mouse to select the boundary(s) you would like to rotate.
When you are finished selecting, press Enter or right-click and select Done Selection.
You will then be prompted to enter a base point for the rotation. Use the mouse or enter the x,y coordinates of the base point in the prompt line.
You will then be prompted to enter a rotation in degrees. The positive convention is counter-clockwise. Enter the rotation in the prompt line and press Enter, and all selected boundary(s) will be rotated about the base point.
To rotate a boundary about any vertex, enter the vertex as the base point (this will leave the position of the vertex at the base point unchanged, and rotate all other vertices about the base point).