lubuntu 19.04 qa-test daily x86 live -- screensaver hiding only primary display (not secondary display)

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1807665

this may still exist; x86 & gone & I forgot, but discovered a 'new' bug
https://bugs.launchpad.net/ubuntu/+source/xscreensaver/+bug/1814490
that may be a duplicate of this one... 19.04 x86_64

2019-02-17 19:30 QA-Test Lubuntu 19.04 daily (live) x86_64

// this [screensaver] issue occurs on my installed system too (Lubuntu only, not when logged in via XFCE/Xubuntu; I rarely use GNOME/Ubuntu..)
// the following is selected bits pasted from my QA-TEST comment
// minor note: vlc is mentioned in a drag - it was playing background music

dell [optiplex] 960 (c2q-q9400, 8gb, amd/ati cedar radeon hd 5000/6000/7350/8350)

..
Now change orientation of displays, pref->lxqtsett->monitor.settings_set.position
DVI-1 is setup directly BELOW DVI-0 (my real setup has slight horizontal diff, but that creates more issues I now ignore for qa-testing; vertical arrangement is simpler to replicate)
drag VLC so it's full onscreen (only left part was visible - ignoring this)..
..

This is my USED system, .. Yes my system is hugely modified (xubuntu & ubuntu are installed, lots of apps, lots of changes but mostly to xfce)...

went and changed screensaver to 1 min, m6502 selected & wait... screen dims then screensaver operates on dvi0 but dvi1 returns to show what is was showing (unhidden).. I didn't have a changing window on that display so will move vlc to that one so I can verify count still changes... https://bugs.launchpad.net/ubuntu/+source/lubuntu-meta/+bug/1807665
opened qterminal (ctrl+alt+T) and maximized, fine on dvi0, but fullwidth & no only top panel (no black area visible on maximized (https://bugs.launchpad.net/ubuntu/+source/lxqt-session/+bug/1809201)
yep htop still displays with count & vlc slider moving as music progresses even though screen has dimmed & m6502 screen saver is running on dvi0

i changed display orientation back to what it booted as (DVI0 on left, DVI1 just to right) and all maximize, minimize, menu showing & usable, etc issues were solved... it relates only to monitor.position and most people will have left-right I bet. (screensaver bug https://bugs.launchpad.net/ubuntu/+source/lubuntu-meta/+bug/1807665 was unaltered! it still shows htop running dvi0 & htop running perfectly visible dvi1 but I've covered this in prior QA-test report. I restarted screensaver deamon (even changed from m6502 to another) & dvi0 is hidden, dvi1 perfectly visible.

logging out. check screensaver says 1 min, open two terms & have htop visible on both (one per display) & wait... -- nah https://bugs.launchpad.net/ubuntu/+source/lubuntu-meta/+bug/1807665 still effecting screen. Alas I didn't test this before altering display.position...