Draw perfect lines and shapes by freehand.

1. Open a notebook.
2. Tap the Pen Tool. Select the button Adjustment in the popover. Make sure the Auto Shape function is on. 
3. Adjust the Delay function of how long you need to hold your pen to alter a hand drawn line or shape to a straight line or a perfect shape automatically.
4. Tap a colour on the toolbar as your choice for your pen.
5. Draw a line and then hold your pen for, for example, half a second. A line between the start point and the end point will be straightened, or a shape will be formed automatically.