I only recently suffered a muckup on my opensuse leap install, so a day ago
switched to openSUSE Tumbleweed.  This is using LXQt desktop

My box is hp 8200 elite sff (i5-2400, 8gb, nvidia quadro 600)
Two 1920x1080 displays attached, with one display above the other.

On install, what was the 'default-right' display is moved in my case below the
default-left display. This issue only appears after that change

When windows are on my lower display, if I click 'maximize' they go full-width,
but use only maybe 1/6th of vertical of the screen meaning for this firefox
window I see the
- title bar
- menu (file-edit-view..)
- my tabs
- address bar
- the title line Bugzilla-Enter.Bug:opensuse.Tumbleweed
then end of window. None of this pages detail text where I'm entering this will
be visible.  This occurs for vlc & other programs (it's not specific to
firefox; it's just the open window I'm clicking on maximize to describe this
behavior).

I'd like maximize to work as it does on my top display; making windows use the
full display.  This issue only occurs after I changed my displays so what was
the right-display on install is marked to be below the left-display.

// note: for my attached picture; my lower display is also aligned slightly
left of the top display which is why there is space to the right of it. The top
display has the panel occupying the full width of my display, the maximized
firefox window shows is full width of my lower display (but only using a tiny
fraction of the vertical space - reason for bug-report).

I can be contact for more detail, or to clarify anything.
Also note this occurs on Lubuntu 19.04
https://bugs.launchpad.net/ubuntu/+source/lxqt-session/+bug/1809201