The Set First Edge tool sets the first edge of a face to the currently selected edge. This step is often needed to orient a face's zero edge toward a street (for example, for placing a building's front correctly). If a face is selected, the highlighted gradient line indicates the first edge (with gradient from vertex 0 to vertex 1).
Click Shapes > Set First Edge in the main menu.
The first edge of a shape is highlighted in orange. The first edge of the shape is always defined as Index 0. |  |
After the tool is applied, the first edge is now the bottom horizontal edge. |  |