Opening Poly Tool
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To add an opening:
- Click on the wall to locate the first corner of the opening.
- Click several more times to place all of the other corners except one.
- Double-click to add the last corner.
To edit the shape of the object, double-click on its outline. In the editing mode, you will be able to move, add or delete corners of the outline.
Detailed info:
The 2D Elevation View