I've got some answers now.
There are some known defects in Compiz and its interaction with xfce panels. One problem is that dragging windows across workspaces does not work anymore, perhaps not even in Compiz with Unity. Also, the Compiz Viewport terminology is not understandable to the XFCE4 panel. There is a patch on Arch linux systems, a special package : xfce4-panel-compiz. However, I've tried to apply same patch to Ubuntu's current xfce4-panel package and it fails with fuzz, so no joy to report. There is an Ubuntu bug report related to this, as discussed at Can't drag windows to another workspace on Ubuntu 16.04
There are 2 vital elements in the Compiz configuration. To my surprise, I had discovered this in 2015: (Compiz, Multi-Head, Workspace Backgrounds and Success: compiz wallpapers changed via python script), but forgot. Back then, I quit using Compiz because of the failure to interact well with the XFCE4 panel, which is still a problem, but there are 2 tips that make the experience much better.
In the current Compiz configurator, ccsm, chose "Preferences" on far left, and change these defaults:
Backend: GSettings Configuration Backend
Integration: Uncheck "Enable Integration into the desktop environment"
The backend issue affects user-written scripts to do chores like change the wallpapers. In my experience, the gsettings config backend is much much better and more stable, the dbus backend used to work great (circa 2012), but now Gsettings is the way to go!.
Turning off integration, of course, may cause other problems I don't understand yet. It may cause complications in interaction with XFCE4 panel, for example. However, that does not seem to work anyway. It appears to me that the desktop integration emphasized in current Compiz is for the Ubuntu Unity environment, not for XFCE4.
- The DBUS backend in Compiz is not workable. If you are going to write scripts to change backgrounds and such, it is much more like to succeed if you use gsettings rather than dbus. I've written the background changer program both ways and in Compiz, there is a problem in re-assigning the image array through dbus but it is not failing in Gsettings.
So my Python scripts mentioned in the 2015 blog post still work if you change to the Gsettings backend.
I cannot get the Compiz cube or rotate cube features to work at all now, but the Desktop Wall works fine and I'm happy enough with that. Wobbly windows is worth it.
Compiz generally has a panic attack if you suspend the computer on one monitor, and then go to another place with two monitors and try to resume a session. The problem is that the system is "aware" of the fact that there are two monitors, but, at least in my Dell 5510, it does not use the 2 monitors. Instead, it tries to show both desktops on the one laptop monitor. The two displays fight with each other, causing some unhappiness. The mouse is not useful here, but it is possible to use the keyboard to launch "arandr" and choose video settings. After that, it works fine.
These are the Compiz modules I have turned on.
Composite
Gnome Compatability
OpenGL
Desktop Wall
Viewport Switcher
Animations
Fading Windows
Window Decoration
Wobbly Windows
JPEG
PNG
Compiz Library Toolbox
Regex Matching
Mouse position polling
Session Management
Wallpaper
Workarounds
Application switcher
Scale
Move Window
Resize Window
Place Windows
Conspicuously, note that DBUS is not turned on anymore.
Conclusion:
After a lot of fiddling around, I'd say Compiz does work and the only major limitation is that the XFCE panel workspace switcher does not work well with it.
I'm going to try harder to apply the Arch linux patches for XFCE4 panels.
Best Answer
My answer is based on Mik's** very thorough response here: What is dconf, what is its function, and how do I use it?.
I'm assuming that your Xubuntu is a default one and that you are using Network Manager with nm-applet.
To reverse the action of clicking "Never show this notification again", open your terminal and paste in the following:
The status will be returned to you. In my case, the response is "false".
In your case, to revert to seeing the notifications again, now paste in the following:
Alternatively, you could just reset the value to the default by using:
You may need to disable networking and renable it or log off and log in again or reboot for the changes to take effect.
Edit: there is a GUI if you want to avoid using the terminal. It's called
dconf editorand you can get it from the software center or by running:Again, Mik's answer describes its usage but, at least in the past, there have been instances of confusion: an example is here: Are dconf schema names case-sensitive?.
**Mik has asked for his account to be deleted according to this.