CTRL + function keys do not work on XFCE4

I am developing a tiny application using GtkD (https://gtkd.org) and after some time trying to figure out why none of my CTRL+Fx shortcuts work decided to test my theory that XFCE4 for whatever reason does not propagate those to my application. I started a GNOME session, and CTRL-F6 shortcut worked. So, I am quite sure it is something in my XFCE4 environment that is causing this. Since I never messed with keyboard mapping it must be some default XFCE4 setting that is causing this.

I tried few other applications, just to check whether my theory (Gedit, IntelliJ IDEA, and VS CODE) and in none of these applications CTRL-Fx shortcuts worked on XFCE.

Any idea how to enable CTRL+Fx shortcuts when I run XFCE4?

Got an answer on the XFCE forum: CTRL-F6 shortcut gobbled up by XFCE / General discussion / Xfce Forums
In short, XFCE reserves CTRL-Fxx for switching workspaces (1 to 12).