How can I send a window to a different workspace without changing the active workspace?

Solution 1:

I am not using Gnome right now, but I see under Focus or open window in gnome on keyboard shortcut that wmctrl works with Gnome.

So, I paste from an answer under the question you linked (on Xfce):

Move active window to workspace 1:

wmctrl -r :ACTIVE: -t 0  

Move active window to workspace 2:

wmctrl -r :ACTIVE: -t 1 

Move active window to workspace 3:

wmctrl -r :ACTIVE: -t 2  

Etc...

Solution 2:

As per the linked QA

wmctrl -r :ACTIVE: -t 0  // Move active window to workspace 1
wmctrl -r :ACTIVE: -t 1  // Move active window to workspace 2
wmctrl -r :ACTIVE: -t 2  // Etc...

Building upon that, here's a command using wmctrl that sends the currently active window to the next workspace (relative), without changing the currently active workspace.

wmctrl -r :ACTIVE: -t $((1+$(wmctrl -d | awk '{ if ($2 == "'*'") print $0}' | awk '{print substr($0,1,1)}')))

To create a shortcut for a command is actually quite simple: Open "Settings" > "Devices" > "Keyboard" and scroll down to add a shortcut.

If the shortcut does not work in that way, but the command works when run from the terminal, save it in a file /fullpath/myfile.txt and set bash /fullpath/myfile.txt as the shortcut command. That should work both on Gnome and Xfce.