GGU-3D-SSFLOW: "Depths in section" menu item

After defining a quadrilateral, all nodes within it can be assigned new depths. Select the action required from the following dialog box:

• "Assign default depths"
  The default depths are assigned. This alters the depths at the selected node for all planes.
• "Raise active plane by dz"
  The depths of the selected nodes are raised by the value dz given for the active plane.
• "Set active plane to z"
  The depths of the selected nodes are set to the depth z given for the active plane.