Add Freehand Sketch
After clicking the Freehand Sketch button in the Diagram window toolbar, the cursor will show a plus. Move the cursor to the start of the sketch and press and hold the right mouse button as you move the mouse to prepare the sketch. The drawing is completed when the mouse button is released. The sketch can be selected in Development mode (toolbar is visible) and then dragged to a different location. It can also be resized, flipped, or rotated by right-clicking on the sketch and selecting Properties from the popup menu.
See also: Add polyline