How to debug 'stuck workspaces' issue in Ubuntu 14.04 inside VirtualBox?

Question

I use Ubuntu 14.04 in VirtualBox (both on 4.x and now 5.0.x) and have encountered a minor buglet with workspaces, and would like to try to trace it to either Ubuntu and VirtualBox, so a fault can be reported. If there is a setting/fix from someone who's experienced the same, that would be ideal.

When I start the virtual machine, it is automatically set to full-screen. Inside the VM I can arrange windows for an application, for example Firefox, on various workspaces (I tend to use 3x3). If I turn off full-screen (usually with Host-F) and then turn it back on again, all of the windows of that app will be gathered on the one workspace, and they refuse to stay in new locations when dragged in the workspaces view. In other words, they drag fine, but dropping them results in them "bouncing back" to the current workspace.

I wonder if this is a Unity problem, and if so I may just switch the guest distribution to Mint with Cinnamon. However if it's an issue with Guest Additions then it will need reporting to Oracle instead, so VB developers can look it.

I've tried Mint/KDE and Mint/Cinnamon, and added a different app on each of a 2x2 workspace in a desktop guest machine. I toggled full-screen twice: once for off and again for on, and all windows are still in their correct workspaces. That reassures me somewhat that VirtualBox is not the culprit, and that Ubuntu/Unity looks to be at fault.

I have also tried a fresh guest install of 14.04.2 to perform exactly the same tests, and cannot immediately replicate the issue here either. I expect the problematic guest machine has gotten itself into a state it should not have been able to.

Answer 1

I have not had any luck in fixing this (and given that my VM is due a rebuild I may just switch to Mint) but I have discovered that toggling the maximised state of windows 'unsticks' them. Perhaps this is a rare bug that results from using Unity inside a VM.

I have written a script to toggle all windows, so working around this bug is now much easier:

#!/bin/bash
#
# Resets all Windows after triggering Ubuntu/VirtualBox windowing bug
#
# @todo Filter out windows we don't need, using grep

for window in `wmctrl -l | cut -d " " -f 1`; do
    # Debugging
    #echo $window

    # Looks like doing just one axis doesn't work
    wmctrl -i -r $window -b toggle,maximized_vert,maximized_horz
    wmctrl -i -r $window -b toggle,maximized_vert,maximized_horz

    # Activate them as well
    wmctrl -R $window
done

Further answers here as to how to investigate this are very welcome, but in the meantime I have logged a bug with the Unity developers.