I am using gdm (Gnome Display Manager) and gnome3 (regular, not classic) on Ubuntu 16.04.
After switching from Unity, I am not able to see any window decorations on all windows.
I cannot resize the windows correctly and I have seen no option on how to turn this on in the Compiz Settings Manager and in the Gnome Tweak Tool.
Here's a screenshot of the issue, as you can see there is no window border.
Install gnome-tweak-tool
sudo apt install gnome-tweak-tool
In the appearance section, reset GTK+, Icons, Cursor