If you're using Compiz/Unity, you can do this from the infamous CompizConfig Settings Manager, but it's a bit tricky.
The "Decoration Match" key in the Window Decoration plugin specifies the windows that do have decorations. To selectively disable window decorations you have to construct an expression that matches every window except the ones you want to disable.
For example, if you want to disable window decorations for windows whose titles end in "Mozilla Firefox" or "Chromium", you can set the decoration match to:
(!title=Mozilla Firefox$) & (!title=Chromium$)
Complete documentation for Compiz window matching is at http://wiki.compiz.org/WindowMatching
Use this command to change the desktop environment:
sudo env XDG_CURRENT_DESKTOP=UNITY nautilus
To make it permanent, just copy the file with:
sudo cp /usr/share/applications/nautilus.desktop ~/.local/share/applications/
for copying /usr/share/applications/nautilus.desktop to ~/.local/share/applications/
Then run gksudo nautilus where gksudo because you run GUI app.
Or,
cd ~/.local/share/applications/ && gksudo nautilus .
where dot will point nautilus to directory. Or even:
gksudo nautilus ~/.local/share/applications/nautilus.desktop
And change the lines:
Exec=nautilus --new-window
To:
Exec=env XDG_CURRENT_DESKTOP=UNITY nautilus --new-window
Save file and enjoy your Unity.
Best Answer
It is. A main compiz developer had previously spoken against it here, so it's obvious that with him also working on unity, this "feature" would be dropped.