Vector Polygon Tool

Activate the tool, then select consecutively at least three existing points (or click at least three distinct positions in the Graphics View) which will be the vertices of the vector polygon. Click the first vertex again to "close" the polygon.

The generated polygon will keep its shape and size when its first vertex is dragged, while when other vertices are dragged the polygon will change its shape and size.

Holding down the Alt (MacOS : option) key after selecting a vertex of the vector polygon creates the next vertex such that the side between these two points makes with the preceding side an angle that is a multiple of 15°.