When attempting to draw the Bank Note in Bah's book, I click on the Circle tool, press CTRL key, and expect to be able to draw a circle. I get noting close to a circle!

Why?

If you hold down the Ctrl-key you constrain the ratio to fixed values (steps). If you keep an eye on the notification area in the status bar at the bottom of the screen while you draw your ellipse, you can see exactly what happens.

A circle is constrained at a ratio 1:1, but the Ctrl-key allows just as easy 2:1, 3:1, n:1 or 1:2, 1:3, 1:m or m:n where m and n are whole numbers.

To draw your circle: hold down the Ctrl-key and drag and keep the ratio to 1:1. It is quite easy to see if you are drawing an ellipse or a circle.

Some other hints:

• holding down the Shift-key draws the ellipse from the centre point, this is sometimes easier. You can hold the Shift and Ctrl-key at the same time to draw a fixed ratio ellipse from the centre.
• if you have troubles drawing a larger perfect circle with the ellipse tool, you could just draw a smaller one, and then use the Select Tool and drag the handles while holding the Ctrl-key down. Now the scaling is uniform.

Cheers,
Syllie

Another quick tip:
Use a grid and activate snapping to grid. You could have the bounding box snap to the grid, or you could have nodes snap to the grid. Either way, the grid will help you to see that you're getting a perfect circle (because it's easy to see that it's inside a perfect square). Plus if you have the snapping set for a strong snap rather than a weaker one, you'll find Ctrl has a stronger effect....or I should say that's been my experience. HTH