Noob here with Lubuntu 18.10. I set up a desktop with two panels - one at the lower display edge with several widgets and another at the upper display edge with just a Task Manager widget. All works OK but when I reboot the PC the upper edge panel appears across the middle of the display.
Additional information in response to questions asked:
1) Problem occurs with fresh install on laptop and desktop.
2) Laptop screen size is 1366x768. Desktop screen size is 1920x1080.
3) Problem still occurs with sudo service sddm restart
A chance discovery showed a connection between this problem and the "Margin" values in Openbox settings. Experiment showed that it occurs if (and only if) the top and bottom edge margins are both set to values greater than or equal to the "Size" of their corresponding panels. If either of those margins is set to a value less than the corresponding panel size then the problem does not arise. Unfortunately that is not really an "answer", because for clarity I want top and bottom edge Margins that are both at least two pixels greater than the panel Sizes that I am using.
A similar problem occurs when the panels are put at the sides of the display. I have not yet determined the exact margin sizes that cause that to happen.
What must I do if I want to use top and bottom edge margins that are larger than the Panel Sizes?