When you are creating a polyline, press the Tab key or click the start node to create a closed polyline and form a polygon.
To create a polygon from an existing open polyline:
- Select the polyline that you have created.
- Select Vector > Node Editing to enter node-editing mode.
- Click and drag the green start node to meet the last node in the polyline.
- When the start node is hovered over another node, the cursor changes to
. Release the mouse button to join the start and end nodes.
You can also create polygons from existing open polylines using the options on the Vector > Close submenu.