I select a system, click "delete", it deletes a random system within the unselected systems and not the one I selected for deletition. Lost a good one to this bug, boo (Because I kept clicking delete until I realized it deletes my precious systems!)
It's weird that deletion working at all. For me it's broken since Uber added "default" systems: PA#3225
I see why it's broken. It combines the 'user' and 'premade' systems, putting the user systems after the premade systems. Then it uses the positions of those systems to delete systems from the original list of 'user' systems. E.g. If there are 7 premade systems, and you delete your first system, it will try to delete the 8th user system. Definitely don't use the delete button.
I was just going to post about this annoyance! I find that the editor always deletes the last system on the list regardless of which system you highlight to delete. Also I find some of my systems are un-deletable! (not referring to the pre-made systems either)
