I found that Notepad++ running in Ubuntu was slow and had undesirable delays here and there.
So I looked into Atom editor but (I think it might be because filesize of my mocked up file being too large it would sometimes generate parameter list other times would not).
Most successful test was in Sublime 3 Editor (after installing Jedi Python something plugin) so that it's Python context sensitive.
Now I have auto complete for Sublime 3 ($80 US cost if you plan to continue to use it).
Here's a quick video of me testing out autocomplete Sublime 3.