Agree, this is definitely a bug, and one that's been around for quite a few versions. I see it from time to time, when there is a "changed trajectory" somewhere nearby, due to an upcoming planet encounter. Sometimes I find that if I move the mouse around enough I can eventually find ~somewhere~ on the blue line that I can add a node. Possibly related to this: sometimes the place the "blue dot" appears is a little bit offset from the "blue line" Does anybody know if there's a bug report somewhere for this? I was just wondering about adding one, but am not really sure what to look for to see if it's already been reported. I feel it must have been, but on the other hand it's been un-fixed for quite a few releases. If relevant, I see this on OS X, and I play in non full screen mode...