Hi, @Joao_Jose_Ribeiro_Ro (João José Ribeiro Rodrigues)
You wrote:
I'm Portuguese but I have a regular (European) 105-key Portuguese keyboard so I don't have the problem you're facing. Having said that, I've found the following somewhat related discussion here in the "Ubuntu MATE Community", that was started on March 2021 by @nicolaigideon (Nicolai Gideon):
On that discussion, after several replies by several users, @Geus wrote the following answer, asking @nicolaigideon to make sure that the "Keyboard input method system" in the "Language Support" is set to "IBus":
Here's the screenshot that @Geus included in that reply:
So, @Joao_Jose_Ribeiro_Ro , I suggest that you check, in your "Ubuntu MATE 22.04", if the "Keyboard input method system" in "Language Support" is also set to "IBus" and, if it isn't, then try to change it to "IBus". I've checked my configuration, in "Ubuntu MATE 22.04" (Jammy Jellyfish) and it's also set to "IBus". To do that:
1 - Click on the Ubuntu MATE Menu, hover your mouse over the "Preferences" menu to show its options, and then click on the "Language Support" icon in the right column), as I show in the following screenshot (you may have to scroll down a bit in the scrollbar on that right column to get to "Language Support"):
2 - That should have opened the "Language Support" window. In that window, please check that the "Keyboard input method system: dropdown list is set to "IBus. Here's the screenshot with the tooltip that appears when you hover your mouse over the value of that dropdown list.
If that "Keyboard input method system: option is not set to "IBus", then try to change it to "IBus" (unless you have a particular reason to choose another keyboard input method) and then click on the "x Close" button in the lower right corner of that window.
After doing this, I don't know if you need to reboot (or at least to log out and log in again) to apply the changes, so I suggest that you reboot, just in case.
I hope this helps. Please, report again later to tell us if doing that has solved (or not) your issue with accented characters