monitor settings have touching screens but gap shows between them

[guiverc]

Synopsis

There is a 'hidden' gap between my displays which shouldn't be there.

I've only had it occur with landscape+portrait(left) display, and occurs only with a specific left-right screen positions (ie. swap the left & right and issue doesn't occur).

Description

The Monitor settings have been adjusted to match (see https://bugs.launchpad.net/ubuntu/+source/lxqt-config/+bug/1882411/+attachment/5381128/+files/screen.jpg) with APPLY already pressed. I cannot move the displays closer (Keep.monitors.attached is clicked), yet windows disappear as if a gap exists between displays, and I have to keep dragging mouse to left awhile to get from my.right monitor before it appears in my.left monitor .. the gap correctly portrays to the BLACK dark section seen in screen.jpg

Expected Results/behavior

Mouse should move between my.left and my.right monitors as if there is no gap, windows should not disappear (you cannot see left edge of Monitor.Settings window in screen.jpg) in this gap..

Actual/Current Results/behavior

There is a gap between the monitors, so I have to drag the mouse some distance to go from the right-edge of the left-monitor before it reaches the left-edge of right-monitor. Also if you drag windows between in that area, the middle of the window is not viewable.

Steps to Reproduce (for bugs)

• boot a system using LXQt with two displays/monitors
• make one monitor landscape, the other portrait-left, click apply

NOTE: Issue may not occur for some boxes; on these boxes you'll need to

• swap left & right position (relative to each other)

Context

It makes LXQt harder to use as mouse movements between monitors require way more movement (to move a single pixel may need 10-20 cm of mouse movement when hidden-gap exists between monitors), and small windows (eg. monitor.settings) can get lost if accidentally dropped when being dragged in this blind-spot.

(technically; monitor.settings won't get lost; it's large enough to be seen on any system I've tried, using it as an example - it'd need to be a very small window to get lost; and the panel-right-click MOVE works to allow moving the windows - but gap makes movement hardware as you cannot see the window)

The issue occurs regardless of WM in use; most testing was with openbox (default for lubuntu), but I also tested using xfwm4 (inc. on debian, opensuse) & fluxbox. See https://bugs.launchpad.net/ubuntu/+source/lxqt-config/+bug/1882411

System Information

• Distribution & Version:
  It was first noticed on Lubuntu groovy (20.10; LXQt 0.15) and exists in hirsute & impish
  It was confirmed in Debian testing (really bullseye/sid), and opensuse tumbleweed (LXQt 0.17)
• Kernel:
  5.8, 5.11 (lubuntu), 5.10 (debian), & 5.12 (opensuse)
• Qt Version:
  0.15/0.16/0.17 (ubuntu, ubuntu/debian, opensuse)
• liblxqt Version:
  5.15.2/5.15.2 (listing only later lubuntu & opensuse)
• lxqt-build-tools Version:
• Package version:
  opensuse: lxqt-config-0.17.1-1.3.src.rpm
  lubuntu: lxqt-config 0.16.1-1ubuntu1

Apologies for any errors, ask for queries, but initial bug report can be found at https://bugs.launchpad.net/ubuntu/+source/lxqt-config/+bug/1882411 (parts of this are copy/pasted)

[guiverc]

I just experienced this issue on a 20.04.3 QA-test install; so it existed in lxqt 0.14.1 too