To correctly set up Compton in i3, follow these steps:

1. Install Compton:

   sudo apt install compton
   

2. Create a Compton configuration file:

   touch ~/.config/compton.conf
   

3. Open the Compton configuration file in a text editor:

   nano ~/.config/compton.conf
   

4. Add the following lines to the configuration file:

   # Basic configuration
   backend = "glx";
   vsync = "opengl-swc";
   
   # Opacity settings
   opacity-rule = [
       "0:_NET_WM_STATE@:32a *= '_NET_WM_STATE_HIDDEN'"
   ];
   
   # Shadow settings
   shadow = true;
   no-dnd-shadow = true;
   no-dock-shadow = true;
   clear-shadow = true;
   shadow-radius = 7;
   shadow-offset-x = -7;
   shadow-offset-y = -7;
   shadow-opacity = 0.7;
   shadow-exclude = [
       "name = 'Notification'",
       "class_g = 'Conky'",
       "class_g = 'Cairo-clock'",
       "class_g = 'Xfce4-notifyd'",
       "class_g = 'Xfce4-power-manager'"
   ];
   
   # Fading settings
   fading = true;
   fade-delta = 4;
   fade-in-step = 0.03;
   fade-out-step = 0.03;
   fade-exclude = [
       "_NET_WM_OPACITY@:32a"
   ];
   
   # Window type settings
   wintypes:
   {
       tooltip =
       {
           shadow = false;
           fade = true;
           opacity = 0.9;
           focus = true;
       };
   };
   

5. Save and close the file.

6. Open your i3 configuration file:

   nano ~/.config/i3/config
   

7. Add the following line to the i3 configuration file to enable Compton:

   exec --no-startup-id compton --config ~/.config/compton.conf
   

8. Save and close the file.

9. Restart i3 for the changes to take effect:

   i3-msg restart
   

Compton should now be correctly set up in i3.