Hi, @lihuto
As I've written before, in another reply from me to you, in another topic here in the "Ubuntu MATE Community" - "How do we test speakers in the new Mate? - #2 by ricmarques" - "(...) The latest available version of the "Ubuntu MATE" Linux distribution is "Ubuntu MATE 24.10" ("Oracular Oriole") - which uses the version 1.26.2 of the "MATE Desktop Environment". (...)".
If you're using the 1.28.2 version of the "MATE Desktop Environment", you're most likely using a Linux distribution that is NOT "Ubuntu MATE".
Anyway, here's a very small video screencast that I've just made of resizing a "Caja" window in "Ubuntu MATE 24.10" using each of the 4 corners of the window at a time:
