Connection tool is only active within the current level/group instead of all the levels

[Danil Sokolov]

To reproduce:
1) Create a Directed Graph with 3 nodes
2) Group two of the nodes
3) Enter the group
4) Choose the Connection tool
5) Try to connect the node outside of the group

Observed behaviour:
The nodes outside the current level are not connectible, even though they are not faded out.

Expected behaviour:
It should be possible to connect across the group levels.