To select Boundary segments

Use the options in the Boundary tab > Selection panel > Type list to specify how segments in the active boundary are selected:

• Select All — Click to select all segments of the boundary (they turn yellow).
• Deselect — Click to deselect any selected boundary segments (they turn white).
• Invert Selection — Select to deselect the part of the boundary that is currently selected and select the part of the boundary that is currently unselected.