Comment 11 for bug 300662

I have this same problem with Teamviewer (Ubuntu 16.04 host, any client). I have tried selecting and de-selecting 'send remote key combinations' to no noticeable effect.

I have also found that disabling 'show location of pointer' either through gnome-tweak-tool or gconf via cli disables the ctrl key almost entirely in the host OS,
ctrl-c (copy),
ctrl-v (paste),
ctrl-a (select all)
ctrl-s (save)
shift-ctrl-s (save as)
shift-ctrl-e (export)
for example, do not work in any application at all afaik

....but oddly
shift-ctrl-up/down (switch workspace)
does work.