To reproduce boot a lubuntu desktop installer and select in Install lubuntu on the menu. Then press a keyboard shortcut to switch to another workspace which are documented on https://help.ubuntu.com/community/Lubuntu/Keyboard but the user has no ui to switch back to the installer other than keyboard shortcuts or mouse middle click over desktop. If we launch install from the menu with one desktop or launch ubiquity so that it shows up on all desktop which can be done in the opebox configuration file this could not lead to users with no buttons and a blank desktop.
Sorry for posting in the wrong place.
I installed Lubuntu 14.04.2 from a USB flash drive. I skipped the "try Lubuntu" option and went straight into the install process. After I set everything up (wipe everything, 315 GB for the main mount point and 4 GB for swap area), I let the computer idle. This was after I picked my username and timezone and so on.
It continued the install for about five minutes, then turned off the display as a kind of power saving feature. (It was on a laptop, but the laptop was plugged in.)
When I came back to check on it, I mashed a few keyboard buttons to wake up the PC and activate the display again. This included some of the arrow keys. Somehow I pressed a combination for switching the visible desktop, because I then saw a window saying I was now on desktop 3. That small window closed soon after, and I was left with just a mouse cursor with the "loading" mouse cursor animation.
When the install was finished, Lubuntu popped up a window on desktop 3 (or wherever I was) and told me to restart. So the install still completed normally.
But I wonder if it's possible to use that same key combination and ruin your chances of a successful install. What if you do it while Lubuntu still needs to ask you questions?
This is not dealing with the part of lubuntu thatis the port to lxqt but rather the defualt settings when choosing install. I get this with the regular lxde version.