Hi Robin, what you're seeing here is the effect of History.

Sometimes it can be a little confusing when the history updates kick in when you aren't expecting it.

Revolve is one of the commands that has history updating turned on by default. This is so you can revolve a curve, and then edit the curve and see the revolved shape update as you move points of the curve around to tweak the shape.

In your case the curve to revolve was the edge of the cylinder, and moving the cylinder counts as a similar kind of edit to the edge curve, so the revolve updates after that edit in the same way it would for a simple curve.

In addition to moving the dome part (which breaks the history connection), you can also turn history updates off on it which will have the same effect to stop the update behavior. To do that, select the dome and run Edit / History, and push "Disable update" - once you have done that the revolved shape will no longer update when its input object changes.

This kind of history update is kind of a tricky thing, some people expect history to be turned on and other people can be surprised by it. I kind of have a compromise right now where history is turned on by default for many of the construction commands, but off by default for some simple transforms like rotate or copy.

re: Revolve Angle - I can't seem to repeat that problem over here, doing a revolve seems to keep the same angle.

However, what you may be seeing is the effect of the revolve going around the same fixed revolve axis. As you move the curve for the revolve, the axis of revolution stays the same which can cause a pretty big shift in the shape as you move the generator curve around.

- Michael