This is probably because you cannot edit galaxies and sprite nebulae in the in-game editor.
The editor only works for stars, planets and so on. And for ray tracing nebulae.
This is probably because you cannot edit galaxies and sprite nebulae in the in-game editor.
This question does not require its own thread.
The nebula editor is for editing raytracing nebulae. These are all procedurally generated nebulae, the names beginning with 'RN'. Really existing nebulae are mostly so-called sprite nebulae and cannot be edited with the editor.
I think it is not possible to select an other object during a 'flight'. But you can cancel the flight with the ESC key and then select another destination.