The root Window is a special Window of the X server. It doesn't have an associated application.
The wiki improperly refers to the root window here. What they meant is a Window that masks/hides the root Window like typically found in modern desktop environments (usually referred to as the Desktop, and often implemented by a file manager showing you the content of a
xscreensaver widgets actually work by updating the content of the root Window. So you need to remove that Desktop window that would hide it and any other Window that is displayed on top of the root window.
What you could try looking for is the process id of the windows that register a "Window Type" of "Desktop" with the window manager. You could do something like:
xwininfo -tree -root |
pcregrep -o '^\s+\K0x\S+' |
xargs -n1 xwininfo -wm -id |
pcregrep -Mo '(?s)Window type:\s+Desktop.*?Process id: \K\d+' |
xwininfo -tree to list all the windows, the first
pcregrep to extract their window id, the second xwininfo to retrieve the WM properties (including Window type and pid) of each and then the second
pcregrep to extract the PID of those Desktop windows).
You could also run:
And click on the desktop. Or even:
And click on the desktop to kill that window.
In any case, note that it may not be safe to kill that window/process as it may very well be handled by some essential process like the window manager.
In the case of
cinnamon, at least on a default desktop environment on Linux mint 18.1 cinnamon edition, it seems to be
nemo though (the cinnamon file manager), so there's little harm killing it.