To move a node of a selected polygon (including a polygonal wall), click the node and use the pet palette’s Move node option.
The two neighboring edges will follow the stretching movement and the shape of the polygon will change accordingly.
To apply an offset on a whole side of a selected polygon, click an edge and use the pet palette’s Offset edge option. This will stretch the neighboring edges.
This offset feature is available for chained elements as well as polygons. Selected elements will be treated temporarily as a polygon, and all polygon reshaping pet palette options will be available.
You can use the pet palette to add to the shape of a polygonal element, or subtract new polygons from it. (This will work on multiple selected elements, too.)
Select the polygon and click it either on an edge or a node. From the pet palette, choose the icon with the + sign (Add to Polygon).
Draw the new polygon shape. It must intersect with the selected one or at least they should have a common edge.
The process is the same for subtracting a shape from a polygon, but choose the Subtract from Polygon icon.