I'm testing compiz compositor in Zorin 17 Lite session.
I have problems with the theme for the windows, especially the titlebar doesn't look good. The Zorin theme is not used. There are shown errors "no default decoration found".
In dconf editor /gnome/desktop/wm/preferences/theme
is shown "This key is deprecated and ignored"
Compiz is aging and while still good, it is not formatted to XFCE all by itself. Compiz requires Metacity; Which there is no Zorin Metacity theme in the current Zorin OS Versions.
Compiz will replace XFWM4 when applied.
I also tried with Jade-1 gtk theme which has a metacity theme included and set it in Zorin Appearance as theme for apps, but still get the error that the metacity theme adwaita couldn't be found.
What happens if you run (Make sure that Jade-1 is the correct name)
gtk-window-decorator --replace --metacity-theme Jade-1
I get an error that no valid metacity theme Jade-1-Red was found.
It seems to be difficult to get compiz properly to work on Zorin 17 lite. Picom was better.
I did a trick now and put all folders from Jade-1-Red theme into the Adwaita theme in /usr/share/themes (and removed those from Adwaita), and the windows look better now, but window buttons for hide and maximizing are missing now, also the blue shadow for inactive windows.
Compiz can take a lot of configuring and it has been a few years since I have used it. I am wracking my brains here to remember how to operate it.
Even back then, I only tried it out. I did not use it regularly.
You may just be better off with Picom. Compiz is fun to play with. But not to use daily (IMO).
Yes, it has many effects which are nice, but I don't need them. What I was looking for, a radius for rounded corners or a plugin for setting up colored borders, seem not to be exist. Only the shadow can be set in different colors for acitve and I am windows so that you get something similar as a colored frame.
I noticed many bugs and strange window behaviour. Maybe I have turned on too much effects.
Now I tested a emerald theme in compiz. It is interesting that you can add invisible mouse grabs there for resizing the windows in any width on all sides of the windows you want.
In emerald it is possible to change the colors and width of the window frames in a theme. The radius doesn't look as set up. I'd need more time to find a good look.
I'd be interested to know which window managers or compositors support this invisible grip area outside the window. Are there any others besides Mutter and Compiz?
I think the way the Emerald Themer works is cool. It would be great to have something like that for xfwm, so you could easily change the colors, shadows, window buttons or opacity for active and inactive windows, height of the titlebar... Unfortunately, it doesn't work as it should for the window bottom radius.
Unfortunately, I haven't figured out how to tile windows yet and why some windows just disappear (fade). I'll try Compiz again in the next few days and enable fewer effects then.
Gala and Kwin do, as well.
Which one of the window managers with invisible grip area is good to use in xfce?
I read that kwin is difficult to set up and many dependencies are required, for gala you need to add the elementary-os ppa to install it, compiz is old, tiling is difficult to setup and the Emerald theme-manager doesn't make the correct radius at the bottom of the windows, mutter makes no consistent look of the windows across various apps and you didn't recommend it...So is there a good option at all (beside creating a xfwm theme)?
Until now, for me the solution with enabling the csd is still the best and easiest way to get a wider grip area for many apps and to be able to switch between themes.
Picom is a good choice for more customizable settings for transparency, shadows, blur and rounded corners. I haven't tested yet if picom causes performance problems, e.g. when watching videos.
I think OpenBox does via configuration - allowing a 1px Border visible, with a wider grab area.
I tried Sparky Linux with openbox in a distrosea live session. In the openbox settings configurator I found nothing, but in the themerc file of openbox.
It was super easy to increase the border width from 1 px to 10 there or to set a 1 px border with a padding inside of the window for resizing or to set up different border colors for active and inactive windows. Very flexible and not so difficult to understand. But the look is not as elegant as in mutter where the grab area is outside of the window.
Now I tested openbox together with picom compositor (for the rounded corners and other transparency/blur effects) in Zorin 18 live session with xfce4 desktop:
I really like it. I installed some openbox themes from archcraft,
here you see the quogir light theme. I have to find out how I can make the handle area at the bottom in the same look as the window, but it is very useful. Then I don´t need wide borders on the right and left side. Perhaps I even don´t the grip at the bottom, because the resize area at the top is really huge and I can use that instead.
I'm not sure if there are also window tiling functions for openbox. At the moment there are no ones.
Edit: In github I found a .config file for the rc.xml file to set up some tiling functions. I copied some into my file, and now I can tile windows with SUPER+arrow keys. It's not so comfortable as in the GUI settings of xfwm4 to set up keyboard shortcuts for apps and windows...
What's next you want to test. Beryl and Emerald? 
I've already tested Emerald, not sure, what will come next. 
Is there a Zorin openbox theme which has the look of the current Zorin windows? Can I use one from the old Zorin versions with openbox or are they too old and don't fit to the current Zorin gtk theme of the window?
How can I make that all apps have the same look and also have the colored borders? The gnome apps don´t follow my customized quogir openbox theme. When I enable gtk3-nocsd, the window buttons get lost and it doesn´t help to show the colored borders and the quogir openbox theme. Do I have to set that up in the gtk.css file?
With gtk3-nocsd:
Without gtk3-nocsd:
I´d really like to find a solution for those apps, because I'm impressed of openbox in combination with picom. It is highly customizable. Even the windows show the colored border when tiled
What strikes me, however, is that all the Windows decorations - such as the Windows buttons - aren’t particularly attractive in any of the themes and are very basic. There are no subtle color variations in the circular buttons; instead, they’re all just black-and-white XBM files. So there are no nice rounded circles for round window buttons.
But you can more easily change things in the openbox themes, and that is what is good for beginners like me.
I have liked Compiz, but not everything works with it, and thats because the last time the APP had an update, was before Zorin OS 16 became a thing. With that said, I am not surprised your not getting much joy, on OS 18 with it. I bet Compiz will stop working completely, when Gnome 50 gets used, in the next OS 19 release.
Compiz is abandonware at this point. I don't know why the creator abandoned it, but not all developers maintain their projects longer then 5 to 10 years.
What a pity that more and more good functions get lost.
I'd really like to know if using a different window manager or compositor in Zorin has a negative impact on performance. Yesterday, during the XFCE live session of Zorin 18 with openbox and picom enabled, the fans ran nonstop while watching videos. I'll test that on my Zorin 17 system, too. Or maybe I'll try it with a live session of Bunsenlabs - this distribution uses openbox and picom by default (but the settings are much more difficult to use than in distributions with a desktop environment as XFCE or LXQT, often there is only linked a config file to edit).
Edit: I decided to give Archcraft a try in a live session with a bootstick, because it has a nice desktop and many themes, but my fan was permanently running while just making settings (and no blur enabled). It was my first attempt with an arch based distro, but it is the same as with debian based ones...not good 
Edit2:
Next test with a live session of Bunsenlabs. This is the first Debian-based distribution where the fan doesn't run constantly on my old Dell... So the first impression is good.
Today I installed xfce on Bunsenlabs and replaced xfwm4 with openbox and picom:
Can anyone help me with the Gnome apps? How can they show the Openbox theme?
Gnome apps will force CSD unless force is applied to stop them. Just as with XFCE using XFWM4, you would need to use a nocsd qualifier, such as gtk-nocsd.
It didn't help here. Do I need to add something to autostart or in a configuration file? Some posts above you see how it looks with gtk-nocsd, e.g. the text editor.
