The rotated working plane can now be used for drawing an object, such as a staircase, for instance. 

After setting an appropriate placing grid - use the ”Grid snap properties“.

Start with the design of a staircase using the command “Place new prism“.

Draw object in the 3D view

Each mouse click on your working plane creates a new point. 

After you have defined the last point, terminate with “return” or double click the last point. 

To exit the edit mode, press “ESC“.

Note: during the “draw cube with the mouse“ command, you can undo wrong entries with “backspace”. 

Enter your input with “return” or double-click the last point.