That is not how point releases for an LTS work. Point releases will included updated packages for that release, in this case Focal. It will also include major bug fixes that are approved by the release team.
New MATE packages, using your example of Caja, are usually updated in the the next major release. In this case 20.10 (Groovy Gorilla) should see new MATE packages as part of the MATE Desktop 1.25.
Ah, Okay Thank you. 
Hello Everyone,
I installed Xubuntu 20.04 on a Lenovo Ryzen 5, but have to do the next:
After booting with usb, open a terminal with Super+t (Windows Key + t) and assign a password (even one character) to xubuntu user, with this command: sudo passwd xubuntu
Press Control+Alt+F1, (it takes to a terminal), log as xubuntu and the password you set in the previous step
Type this command: xfconf-query -c xfwm4 -p /general/vblank_mode -t string -s "glx" --create
Kill the session with this command: killall xfce4-session
After this you will see the login screen, select xubuntu user and type the password you set in step 1, and install Mate.
When you log after install, you'll see the same issue, but repeat the process from step 2. with the user created after the installation.
Hope this helps.
This bug is documented here:
The workaround is explained here:
I have 34" (21:9) display and it's very sad, that such a big bug can occur on a LTS version and affect users for month. I wont to use 2 windows, but without the composit it's a pain in the ass for me....
Sry, but i have to release my frustration about this bug, which was gathered in the past months...
Hi All
Still going strong with new card, no crash. Love the new system.
Perfection is possible, do you remember the Penguin on Cairo on the bottom of the screen.
I would love to see that doing a lap of honour on this Desktop!
Unfortunately, none of the regular QA or Dev Team members has an AMD GPU to test this.
What can be done to supply you guys with such hardware, since this shourtcoming has caused such a visible and annoying issue be let through?
I understand that this bug is very frustrating if it affects you; this particular bug occurs not only with Ubuntu MATE, but at a minimum also Xubuntu and Ubuntu Studio.
The Ubuntu MATE testing team is a small group which is dispersed around the world, who are very dedicated but are volunteers using their own hardware and their own personal time.
While I think it would be great to have team members equipped with systems with AMD GPUs to test, this issue does not occur with all AMD GPUs. For instance I have had a friend try and replicate the issue with an AMD RX 5700 XT without success.
There is almost an infinite number of hardware combinations, testing them all is not realistic or even possible. Different bugs may only occur when using a Macbook, certain nVidia cards, with different wifi devices.
This particular issue shows why we stress filing bug reports and marking existing ones as effecting you on Launchpad. The logs and associated information that is gathered in these reports is invaluable in helping the developers fix these. In turn the more reports that are filed generates more "heat" which helps in getting the needed resources in place to get these bugs fixed. Some of those resources are outside of the Ubuntu MATE team.
We have created threads for the past few releases to involve the community in testing. I urge everyone to join in and test, that is the best way for things to get found and to have the details needed to have fixes put into place.
20.04.1 was released today. Unfortunately this bug was not resolved in this point release.
I did discuss this with members of the Ubuntu release team in irc prior to the point release. This week the Importance of this has been changed to High in Launchpad. That is a promising sign, that said I urge everyone affected by this to continue to update the bug report to continue to increase the 
on this issue.
As I said in the Menu icon thread: I can only speak for myself, but I do apologize that this continues to be an issue.
If I understand well, do you need people with AMD GPU to test or reproduce this issue? If yes, I can ask help on an other Ubuntu forum?
The more people who can test and reproduce the issue and report on Launchpad the better.
I replaced my old nvidia by a radeon RX 5600 XT and I got this bug on Mate 20.04 on stock driver and also with radeon driver downloaded version 20.30. I will contribute to bug report.
As workaround, we can set to marco with GPU compositor compton:
marco-compton
If upgraded from 18.04 to 20.04 compton is still installed.
Hi. Ubuntu Studio (xfce4) user here, but having the same bug with an AMD Radeon 3 display, and the same workaround (switching off the windows compositor). This is the only place I'm seeing the bug discussed in a way my non-nerd brain can understand! I am honestly not sure where or how to submit a bug report so the people who make the amdgpu drivers can get this fixed, so any advice on that would be appreciated.
Unfortunately, with kernel 5.8.7, problem still remain but displayed broken instead of stairs artefacts, with marco.
What is the command for Mate of equivalent of:
xfconf-query -c xfwm4 -p /general/vblank_mode -t string -s "glx" --create
Also, no issue with metacity:
sudo apt install metacity
metacity --replace
Is metacity working as well as marco?
Yes, with shadow effect.
@Wimpy : As you post also with gaming for linux, are you aware of this bug? In view of your role in the Mate environment, will you be able to watch in order to move the fix forward ? With the mesa 20.3 driver, still have issue. It's really too bad to use marco without a compositor without shadow effects with a modern machine, it makes me sad.
Hi,
After using the ubuntu release upgrade prompt to upgrade to 20.04 I experienced gui issues.
Login screen works fine.
After login nothing is readable/displayed correctly except the cursor.
I restored the previous version Ubuntu 18.04.5 LTS.
~$ lspci | grep VGA
01:00.0 VGA compatible controller: NVIDIA Corporation NV44 [GeForce 6200 LE] (rev a1)