Windows become invisible when (dis)connecting external monitor (LXQt)

[laMudri]

Problem Description

I run XMonad in LXQt, with LXQt mostly at default settings. LXQt handles the multiple monitor positioning. When I connect or disconnect an external monitor, all windows, plus the LXQt panel, become invisible. I can make the windows become visible again by jigging around with the layout (for example, opening a new floating window or a new tiling window that causes the master window to resize). For the panel, I have to restart it, I suppose because it's impossible to jig it.

It reminds me of a problem I would have on XFCE, where any windows opened in the first few seconds after start-up (including the panel) would disappear when those few seconds were up. The fix was the same.

Steps to Reproduce

1. Open some windows.
2. Connect an external monitor.

Configuration File

I haven't tested this exact config, but I think it includes all the relevant bits (omitting keybindings and workspaces and stuff):

module Main (main) where

import XMonad
import XMonad.Config.Desktop (desktopConfig)

main :: IO ()
main = xmonad desktopConfig

Checklist

• I've read CONTRIBUTING.md

• I tested my configuration

  • With xmonad version 0.15
  • With xmonad-contrib version 0.16

[hashborgir]

This happens to me on Xmonad in KDE.

I reconnect 2nd monitor, then select a window, it's invisible, then I click the KDE menu icon button, and the window comes back. Try that. Hit the LXQT panel button for application menu and see if the window comes back.

[paradoja]

Something very similar happening also with Gnome Flashback so maybe not something specific to LXQT (windows going invisible, but being able to create a new one and moving it around makes others reappear; the Flashback bar staying invisible, though).

[thongpv87]

I got the same problem with XMonad 0.17.1 + KDE 5.27.

[phil-s]

I'm also experiencing something very similar to this in xmonad 0.15 under Ubuntu 22.04 and Gnome. I've been running 22.04 for about 10 months, and I don't recall this ever occurring when I was running 18.04 on the same hardware (I'm pretty sure I was using whichever xmonad version was available by default in 18.04 at that time).

Unlike the OP I don't believe I've triggered this problem by (dis)connecting an external monitor (which is something I do on occasion), but the trigger might be related to that. In my case it's inconsistent and most of the time I don't suffer this problem; but sometimes when unlocking my screen after xdg-screensaver has kicked in I'm left looking at my desktop background, and all of the windows are hidden. (Or maybe it happened upon locking; impossible to know.)

I'm afraid I can't remember whether this next part is consistent or not, but when the problem occurs there has often been a kind of doubling-up of the screensaver in that I'll unlock it and then pretty much immediately it comes back and I have to unlock it again. The second time will 'work' insofar as the screensaver doesn't kick in again -- but all my windows are invisible.

Like the OP I'd discovered that generating a floating window seemed to reliably make everything in the workspace visible again. (I didn't know about the "resize the master window" approach, so I've not tried that.)

Prior to creating a floating window, I can often get a full-screen window to display if I'm in a full-screen layout; yet switching to a tiled layout would make it disappear again and stay invisible. (I can't tell which layout is in use though, so in practice I would attempt to open a terminal and, if nothing appeared I would switch to the next layout and try again until I had a full-screen terminal or had tried as many layouts as I have defined without success.)

Also similar to the "LXQt panel" part of the original report, my xmobar is also invisible when this issue occurs, but reappears if I restart it.