changing monitor configuration & on next login, only one monitor is fully usable to LXQt

Lubuntu lunar daily QA-test (live) on
- hp prodesk 400 g1 sff (i5-4570, 8gb, amd/ati cedar radeon hd 5000/6000/7350/8350)

this issue is NOT unique to Lubuntu; I've been experiencing it a lot on Debian lately; which is why I looked for it here (tonight) on this LIVE QA-test..

I also experience it on occasion on my primary box; just logout & login again usually resolves it there (in Debian too).

To avoid the issue; replace OPENBOX with XFWM4 or another & it won't occur, thus the filing against openbox.

** To re-create

- adjust monitors (how they are positioned to each other)
- logout
- login

** additional notes

- the logout/login may require a numerous attempts times to occur
- if it doesn't occur in 3-4 logout/login loops; adjust monitor alignment again & try again.
- it's occurred with monitors left+right aligned, top-bottom aligned & other combinations too YET i have had alignments where I DO NOT EXPERIENCE the issue too..
- occurs on boxes where I have 2, or 3 monitors attached
- this has occurred on installed systems (Debian bookworm & lunar), filed when I experienced it on LIVE lunar QA-test
- this bug is EASIER TO REPLICATE when one screen is vertically above another.. most users have side-by-side arrangements so likely won't be impacting many users

** Expected result

- on login, all are both usable, have wallpaper (half/third of wallpaper on each)
- right click on background pulls up menu

** Actual result

here it's inconsistent... Much of the time the result is Expected result

BUT

logout/login a few times & depending on how monitors are positioned you may get

- one monitor (or more) has the expected wallpaper but one is drawn without wallpaper & you're experiencing this issue.
- the monitor with wallpaper will operate normally & can hold windows
- one (or more) monitor will have no wallpaper & thus right-click on background will do nothing
- you cannot drag/drop windows from monitor with wallpaper to monitor that is black
- mouse (pointer) moves over black monitor as expected (ie. monitor exists & will take mouse-pointer normally, but windows won't draw on it if dragged to that window... if windows are dropped here they'll be inaccessible.. but if held & dragged across the black monitor & the drag continues to the wallpaper drawn monitor you can drop & use windows normally
- if panel is on black monitor (with only mouse-pointer being drawn on it) then panel+menu cannot be seen on that monitor/used, but it appears to be working; is just unseen (as are probably windows dropped there).

ProblemType: Bug
DistroRelease: Ubuntu 23.04
Package: openbox 3.6.1-10ubuntu1
ProcVersionSignature: Ubuntu 6.2.0-18.18-generic 6.2.6
Uname: Linux 6.2.0-18-generic x86_64
ApportVersion: 2.26.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: unknown
CasperVersion: 1.480
CurrentDesktop: LXQt
Date: Tue Mar 28 12:22:27 2023
LiveMediaBuild: Lubuntu 23.04 "Lunar Lobster" - Alpha amd64 (20230325)
SourcePackage: openbox
UpgradeStatus: No upgrade log present (probably fresh install)