Why does Draw keep changing my vertices to corner points?

When drawing Bezier curves I start with a line. Then I click on “Add vertices” and add a single vertex. This vertex is added as a corner point. I then select that vertex and click on “Smooth transition.” Usually, after that, any vertices I add are automatically created as smooth transitions. On the particular line I’m working with now, I follow this procedure and after adding a couple of vertices I notice that they have all been changed to corner points. I click on the “Smooth transition” button, but they will not change. I can’t figure out what I am doing differently now. Why does it change my points to corner points and why won’t it let me change them back to smooth transitions?

“smooth transition” does not exist as true property, but it is calculated from the position of the control points. It is only a help for current drawing, you will loose it on saving anyway. “Symmetric transition” is a true property and will be saved.

If you enter a further point, the curve will slightly change. The effect is, that the position of the other control points will slightly change and then the test for kind “smooth” will fail and the point will be set back to kind “corner”.

Ok, that makes sense. I notice that it happens if I add a point inside the handle of the old point it does it. But if I shorten the handle on the old point first it doesn’t. Very helpful to know that smooth is not a property, but symmetric is. Thanks