When I draw a circle and then draw a straight line and I lay the line over the circle through a diameter - they become somehow permanently glued together! I can imagine this might be useful in some cases, but once they’re joined, I cannot find any keystroke that will allow me to move one without moving the other or even deleting one without deleting the other.
How do I separate these things and what is this “arrangement” called?
There are various ways to get objects to automatically join. One is with Magnets. The other is allowing connects to/from lines and other objects. I have these turned off almost all the time so I don’t even remember which exactly snaps them together…
In addition, there are smart alignment guides to help you place objects together.
I would check the connections property for the objects first and uncheck all the boxes on both the lines and other objects pages.
If that doesn’t work, check under “Arrange” if the “Smart Alignment Guides” is turned on.