Hi,
I feel like the bug has been going on and off along the development of 3.6.0: When you select the proxy settings, if you choose directly http, then there is no problem accessing the form for server adress and port. Yet, if you ever go back to direct, and then want to turn on the proxy http again, the form has disappeared and never comes back (exception if you add manually the settings directly in the all-settings window, and then restart Cytoscape).
Yohan.