Unlike translating existing nodes [which disables cursor wrapping and
enables edge-scrolling instead since rBSa1cc7042a745], adding new nodes
would still show the old behavior of cursor wrapping.
This has been disabled for the case when the node whould be added outside (due to menus overlapping other editors).
Now enable edge-scrolling for adding new nodes as well and make sure
this only starts once the mouse has returned into the inside rect once.