Say I make a simple sitemap. Connect the boxes to each other with the line tool. Say I select all of the objects I've just laid out and move them somewhere else on the canvas or copied and pasted them. Sometimes, not all the time, but many times, the lines might totally disconnect from its parent or the lines will stay connected, but the vertical position will get all out of wack. I've checked to make sure I'm not accidentally only selecting part of the set of shapes or lines. I've selected everything. I can't count how many times I've moved stuff and had to reconnect all the lines again and again!