** Background

Originally filed at https://bugs.launchpad.net/ubuntu/+source/openbox/+bug/1845756

Reported initially on Lubuntu 19.10, occurs all releases up to current development (hirsute). Also confirmed on opensuse tumbleweed, Debian Bullseye/sid, Fedora 33

Initially believed to be a LXQt issue, it was filed upstream (LXQt) at https://github.com/lxqt/lxqt/issues/1925 however if openbox is switched out and replaced with xfwm4, or icewm, the issue is gone. To return issue openbox needs only to be used, hence filing here.

** Description

On certain display configurations (one monitor above the other), clicking Apply causes one display to go black, and the other to have half the wallpaper.

Further, a right-click on the monitor that has background causes the LXQt menu to appear, however right-click on the other monitor (that is black) only has Openbox's menu appear

Note: if you reverse the top/bottom display, the issue does not occur.

** Expected Behavior

Wallpaper appear on both monitors (half on each)
LXQt menu appears on both monitors when right-click pressed

** Actual Behavior

On changing display configuration (2x displays, 1920x1080) with one display above the other, on clicking apply you get

- one monitor has no background, openbox menu appears with right-click
- other monitor has half of the wallpaper/background, LXQt menu appears with right-click

** Steps to Reproduce

- Two monitors, 1920x1080.
- (on LXQt) open Monitor.Settings and set one display above the other
- click Apply
- if issue doesn't occur, firstly I'd suggest logout & login again
- if issue still hadn't occurred, swap top & bottom monitors & re-apply. logout & login may be required as well.

(note I've had the logout/login required, and not-required; can't provide clues as to how that relates (insufficient testing-sample-size for picture sorry)

Note: If the top/bottom monitor is in one order, the issue will not occur. If so reversing the top/bottom will have the issue occur.


** Some system information

Distribution & Version: Lubuntu hirsute, Opensuse tumbleweed & Debian Bullseye
Kernel: 5.10.0-14, 5.10.16-1, 5.10.0-3

On Lubuntu, `openbox --version` reports "Openbox 3.6.1"

** For pictures & more detail

refer https://bugs.launchpad.net/ubuntu/+source/lxqt-session/+bug/1845756 but I'd concentrate on comments #10 & later

Top display - https://bugs.launchpad.net/ubuntu/+source/lxqt-session/+bug/1845756/+attachment/5467407/+files/screen_top_menu.jpg

Bottom display - https://bugs.launchpad.net/ubuntu/+source/lxqt-session/+bug/1845756/+attachment/5467410/+files/screen_bottom_menu.jpg