Circle
Circle Guides will allow you to draw perfectly round circles.
To add a Circle Guide, perform a right-click on the Canvas to position the Circle's center (the small blue square represents the Circle's center and matches your cursor position). Once it's done, move your pen to change the Circle's radius and perform a second right-click to confirm the creation of the Guide:
Once created, you will have access to this Guide's options in the Guidelines panel:

tip
The Eye, Magnet, Assist, Assist Show/Hide, Lock, Opacity and Margin functions have been covered in the previous, Overview section.
Here is an example of several circles being drawn using the Assist tool:

The Guideline Panel also allows you to change some of the Guide's attributes:
- The Center X and Center Y fields represent the position of the Circle Guide. It is possible to change these parameters using the mini-sliders on the right or by entering a value into the dedicated numeric fields.
- The Radius parameter will allow you to change the radius of the Guide.