Buggy behavior for selecting network for extension

[khanspers]

In Cytoscape 3.10:

1. Import two networks from WikiPathways
2. Select one of the networks in Cytoscape, let's say "net 1".
3. Go to "CTL Extend network". The interface prompts for "Select user network", but if a network OTHER than the already selected network is chosen, let's say "net 2", things get confusing. The results of the extension is indeed the extension of "net 1" (originally the selected network), but the results end up as a subnet under "net 2". See screenshot.
4. There is also an error message (see screenshot) and the extension doesn't actually work, as compared to a properly selected run.

Related: If no network is selected in Cytoscape, the CTL interface never loads and there is another error message.