Customizing the MATE Panel
Customizing the MATE panel basically works. Mostly.
Customizing requires two distinct efforts: unlocking and moving panel icons. This is clunky because accessing those two options requires using the respective context menu and must be done for each icon involved in moving. Moving an icon to a specific location on the panel is impossible when any other icon in that sequence is locked. Ideally users should be able to move an icon over or past any icon.
Rather than individually lock each icon a simple solution is only lock the panel. Users then could unlock the panel and slide or move any icon on the panel. Then again lock the panel.
There is a panel quirk I am unable to replicate in a repeatable manner. Despite being locked, applets in the system tray area will mysteriously change locations when starting the desktop at different screen resolutions. I have seen this happen often when I copy a user profile from one system to another.