I'm on Ubuntu GNOME 16.04 and I'm using devilspie to undecorate the GNOME Terminal windows. It works well except when a terminal window is launched, it is not focused and shortcuts like alt-tab, alt-`, or alt-esc do not work at all (not even ctrl-alt-tab). I have to click on the window with mouse pointer and then the window is focused and everything is back to normal. I know it may seem like just a minor annoyance but its in the way of me feeling all warm and cozy on my desktop :-)
My .ds file for GNOME Terrminal looks like this:
(if (is (window_role) "borderless")
(begin
(undecorate)
)
)