If you want to learn the details of my long, rambling, experiences with installing and using the LXQt desktop on Ubuntu-based distributions, simply continue reading. If instead you want, based upon my experience, a simple and straightforward recipe for installing LXQt desktop skip to here.
My first experience with the LXQt-desktop under Lubuntu ocurred mid-September, 2016 when I issued the command "sudo apt-get install lxqt" in a virtual terminal in my up-to-date Lubuntu-16.04.1 installation running on an Asus ROG GL752VW laptop, which has a GeForce GTX 960M video card. If I remember correctly, this enabled me to run an LXQt Display Environment (DE) either by issuing the command "startlxqt" from a command line or by adding the line "exec startlxqt" to my .xinitrc file and then doing a reboot. If, at login, I choose the Lubuntu desktop option, I in fact ended up in a LXQt DE.
Instead of getting to a LXQt-desktop as described above, I issued the command "sudo apt-get install lxqt-common", which installed lxqt-common but removed four LXDE packages, so that, upon reboot, the option of logging into a Lubuntu desktop was replaced with the option to log into an LXQt desktop.
There were several problems with the LXQt desktop obtained as described above, not the least of which is that the main menu was confusing because it was filled with many LXDE options that no longer worked. I chose to do a few more steps to simplify things.
Pcmanfm works perfectly well as a file manager under the LXQt DE, but it's configure preferences options do not. I therefore issued the command "sudo apt-get remove pcmanfm" and relied on pcmanfm-qt, installed as part of the lxqt metapackage, as my file manager.
Other packages that no longer worked after doing the above, were lxsession, lxsession-default-apps, and lxappearance, and I chose to remove them, along with lxpanel and obconf, whose functionality was covered by lxqt-panel and obconf-qt.
Even after proceeeding as above, the main menu was still confusing in that it had many entries from non-LXQt apps. It should be possible to correct this by editing the desktop files and setting the OnlyShowIn and NotShowIn keys in the desktop files to appropriate values. Unfortunately, this did not work as it should have, pointing to a larger problem which may or may not be related to this problem here. I also found at least six smaller bugs in Lubuntu LXQt desktop as I installed above.
1) vlc seems to put two icons in the panel when it executes and leaves one persistent when it exits. The persistent icon disappears only when lxqt-panel is killed. A workaround that seemed to help was to add the "--no-qt-system-tray" command line argument to the Exec key in /usr/share/applications/vlc.desktop, which reduced, but did not eliminate, this problem.
2) pcmanfm is able to mount and display MTP items without the package mtp-tools, but pcmanfm-qt requires it and mp-tools is not installed by default. The obvious workaround is to issue the command "sudo apt-get install mtp-tools".
3) Another bug is the previously-reported one that qlipper breaks emacs copying. My workaround was to not autostart qlipper.
4) pcmanfm-qt always treats BackupAsHidden as true, regardless of how it is set. This means the only way to see backup files with pcmanfm-qt is to select Show Hidden. Pcmanfm does not have the same bug, either in LXDE Lubuntu or in my configuration.
5) I also found was that the lxqt-panel keyboard-layout seemd to keep forgetting my second input-keyboard. This was solved by removing both ibus and fcitx, after which everything worked perfectly, even though, as far as I know, I have no "input method" installed.
6) There also was a problem choosing chromium-browser as my default web browser. I went to Menu->Preferences->LXQt settings->Session Settings->Default Applications->Web Browser and tried to enter "chromium-browser". My choice was not remembered after a logout and login. Thinking the problem might be do to insufficient space to store the rather long application name, I copied /usr/bin/chromium-browser to /usr/bin/chromium and /usr/share/applications/chromium-browser.desktop to /usr/share/applications/chromium.desktop, and after a logout and login, I repeated the same procedure and entered chromium as my default browser. My choice now was remembered through multiple logouts, and for the first time, clicking on any of the links in "About LXQt", opened the chromium rather than the firefox browser.
My second experience with LXQt desktop was when I upgraded the above laptop to Lubuntu-16.10. Things seemed to work as previously and examining the numbers on the updated lxqt files, I guessed they were pretty similar to those in the 16.04.1 repository. I then issued the command "sudo apt-get install lubuntu-qt-desktop" in a virtual terminal. This lead to very many things being installed but the installation did not complete do to a problem with installation of plasma-workspace. I may also have inadvertently selected lightdm rather than the recomended sddm as the window manager. The major difference between this installation as opposed to the one with the lxqt metapackage, was that many more choices of DEs were available at login. A few of these choices disappeared after I removed the lubuntu-extra-sessions package, but the Lubuntu and LXDE desktops remained. The resulting LXQt DE however, was still based upon LXQt 0.10 and had many of the same problems as recorded above. A seventh problem was that the power-manager kept crashing so that I could not use it.
My third experience with the LXQt-desktop under Lubuntu occurred at the end of October, 2016 when I did a fresh install of Lubuntu-16.10 on an Asus X75A with a GFX0 video card and then issued the command "sudo apt-get install lubuntu-qt-desktop" in a virtual terminal. This lead to very many things being installed, but the installation, like my experience on my Asus ROG GL752VW, didn't finish as there was a problem installing the plasma-workspace. An advantage to this installation of the metapackage lubuntu-qt-desktop over the previous installation of the metapackage lxqt was that other DEs remained possible at login.
My fourth experience with the LXQt-desktop under Lubuntu occurred on 27 October, 2016, when I did a fresh install of Lubuntu-16.10 on my Asus X75A and then followed the directions for compiling and installing LXQt-Desktop for several distributions using git. This installed lxqt-0.11 nearly flawlessly, following the directions for Ubuntu.
Having had such success on my Asus X75A, I decided to do a fresh install of Lubuntu-16.10 on my Asus ROG GL752VW and follow the same instructions. However, I could not do a fresh install of Lubuntu-16.10 on my Asus ROG GL752VW, with a GeForce GTX960M video card, because it almost never boots up unless I use proprietery video card drivers, and I probably forgot to choose to load the proprietory drivers when using the Lubuntu-16.10 iso. I then did the following: On my Asus ROG GL752VW, I logged into a Lubuntu session and issued the command "sudo apt-get remove lxqt" as recommended in the very informative previously referred to github.com link. I then put all the commands I had used on my Asus X75A into a command file and transferred that file to my Asus ROG GL752VW. That file, called et_install_lxqt_desk, can be downloaded from my website. All you need to do to install LXQt-0.11 under Lubuntu-16.10 is to download the file, make it executable by issuing the command "chmod 755 et_install_lxqt_desk" and, in the same location, issue "./et_install_lxqt_desk". You will probably have to be included in the sudo group or in /etc/sudoers and supply your password. Many of the problems associated with the lxqt and lubuntu-qt-desktop metapackages are no longer present in LXQt-0.11.
My sixth experience with LXQt-desktop was when I did another fresh install of Lubuntu-16.10 on my Asus X75A and then installed LXQt-desktop with et_install_lxqt. This worked perfectly on 29 October, 2016.
My seventh experience with LXQt-desktop was when I used et_install_lxqt_desk to install LXQt-desktop in LXLE. This also went smoothly, and I then had the choice of using the LXDE or LXQt desktop at login.
My eigth experience was on 15 January, 2017, when I erased the lxqt folder on my Asus ROG GL752VW laptop and re-ran et_install_lxqt_desk to upgrade LXQt to version 0.11.1.
My nineth experience was when the many bugs in Lubuntu-17.10, persuaded me to install LXQt-0.12 in Ubuntu-17.10 instead. This produced many surprises, which are described here.
I am not qualified to give a detailed critique of LXQt desktop, but to me it seems to work as well or better than LXDE Lubuntu and I think it is an excellent desktop environment. I am a bit puzzled by Lubuntu's rather tepid approach to providing an LXQt DE. Perhaps they are trying to accomplish more than that. Perhaps they want everything in their distribution to be Qt-based. It seems to me that as of 1 November, the best way to install an LXQt-desktop in Lububtu is to download et_install_lxqt and run it as described above. This still seems true as of 15 January, 2017.
LXQt-0.11 under Lubuntu-16.10 seems to have fewer bugs than LXQt-0.10, but a significant number remain. However, most of the bugs are not in LXQt-0.11 itself, but seem to be related to integrating LXQt with Lubuntu.
One bug that still persists in LXQt, even in 0.11.1, is that pcmanfm-qt still treats BackupAsHidden as always true, regardless of how you set that option in its preferences. The problem here is that you cannot show backup files without also showing hidden files, regardless of whether the "Treat backup files as hidden" option in Preferences is selected ort not.
Another bug is that the technique for setting the wallpaper is a poorly documented. There are three techniques that work. 1) Wallpaper can be set by issuing the command "pcmanfm-qt --set-wallpaper name_of_picture" where name_of_picture is the name of a picture you want as wallpaper. 2) It may also be set by going to the main LXQt menu, then Preferences, then LXQt Settings, and then clicking on Desktop. 3) Issuing the command "pcmanfm-qt --desktop-pref Desktop" gets you to the same gui for selecting wallpaper as procedure 2.
A minor bug is that the mouse sometimes forgets where its focus is. This is corrected by clicking the left mouse button.
A third bug in LXQt-0.11.1 is that, at least on my Asus GL752VW, with a GeForce GTX960M video card, using the proprietary driver, lxqt-config-monitor always crashes with a seg-fault.
The remaining bugs I found using LXQt-0.11 all relate to LXQt's integration with Lubuntu. The most annoying bug I discovered was that if I used lightdm as my display manager, whenever a chromium-browser window sat on top of my own GTK3 app's GUI window, some of its content got written to my window and didn't disappear when chromium was closed or moved away. This problem, however, disappeared when the display manager was changed from lightdm to sddm as described here. Since sddm is considered the "default display manager" for LXQt, it might be a good idea always to switch the display manger to sddm after (or before) LXQt installation.
Another problem using LXQt under Lubuntu is that while the command "xdg-settings get default-url-scheme-handler mailto" seems to work, "xdg-settings set default-url-scheme-handler mailto msmt.desktop" does not. This problem lies with xdg-utils-1.1.1-lubuntu2. That version of xdg-utils has a number of deficiencies. It does not come with xdg-email, which is used by chromium-browser and google-chrome to launch mailto clients, and it also does not recognize LXQt as a valid desktop environment. I have re-written xdg-utils, adding a small amount of code so that it corrects these deficiencies. I downloaded the starting code from portland.freedesktop.org, modified RELEASE_NOTES and four files in the scripts subdirectory (xdg-utils-common.in, xdg-settings.in, xdg-email.in, and xdg-open.in), and regenerated xdg-utils-1.1.1-et.tar.gz, which can be downloaded from here. To install after unpacking the compressed file, cd to the top directory and issue the commands "./configure --prefix=/usr", "make", and "sudo make install". Success of the ./configure step may require you to install the xmlto package, which does not come by default in Lubuntu-16.10.
Another problem I experienced using LXQt-0.11 under Lubuntu-16.10, was that when gtk3 applications, like google-chrome, were launched from a command line, the warning message "Theme directory imported-Humanity/192 of theme Lubuntu has no size field" appeared. This was corrected by editing the file, ~/.config/gtk-3.0/settings.ini and changing the entry "gtk-icon-theme=Lubuntu" to "gtk-icon-theme=Oxygen".