After system reboot, my panel objects are often, but not always, arbitrarily reordered. This happens only to custom objects and only to objects on the right half of the top panel. It happens even to 'locked' items.
Is this reordering a bug or have I missed a feature?
This used to happen a lot on the old gnome 2 and in the earlier iterations of Mate. By the sounds of it, the problem might be reoccurring.
The way round the problem I have always used is to go to the right hand end of the top panel and right click each element and unlock them. Then reposition them so there is a slight gap between the elements. Then re-lock them into their new positions. Then reboot.
The slight gaps between the objects seems to allow them some wriggle room while they populate the panel at login. In doing so, in my experience, it minimises the likelihood of them being re-arranged.
I will give this a try and get back. The 'cramping' is a likely culprit here because I clustered the troublesome objects into a single statement so...