3. You can edit the contour after you have created it. You can edit each segment of the contour. Click on one of the contour points, and then on another one. After the segment is selected, a dialog box with segment length appears. Change segment length and click OK.
Wall length is changed in the direction from the first point to the second one (that is, the first point remains as is and the second point moves according to the specified wall length). Click on 
button to create a room based on the contour.