I have installed Ubuntu Mate 18.04 as a virtual machine under VMWare on a CentOS 7.4 host. It is working quite well. A big thanks to all who contributed! I am especially pleased that Wine 3 is available and will run three 32 bit critical legacy applications for me which have caused issues on CentOS 7. That said…
As I experiment with Ubunt Mate 18.04 I have noticed that ON OCCASION a Right Click on the Desktop will do NOTHING. If I Right Click on an open document in Pluma, a terminal window, an open Caja window etc. the Right Click works. It is only a Right Click on the Desktop itself which does not work.
I believe a Right Click on an object on the Desktop will work but I am not sure and I have “fixed” the issue for the moment by logging out and back in. I will verify next time I experience the issue.
I have not been able to reproduce the issue at will so I do not have enough data to submit a bug report at this time. Has anyone else seen this? Any suggestions?
TIA,
Ken
I’ve seen it, or similar, on various situations but also cannot create it. I think the desktop refuses focus or something. We may be talking the same thing if this is true…
LEFT-click on the desktop first (it seemed to set or force focus).
NOW does RIGHT-click work?
Sorry no more help. I haven’t seen it in quite awhile. Maybe you’ll get lucky to find how to create it. Something almost the same happens on 16.04 on compiz when a Software Update goes active.
Thanks Bill_MI,
I will try that next time it happens. I was just building a new virtual machine. I had some updates and installations going on in one terminal and was editing /etc/hosts with vim in another. I tried to copy my standard list of addresses from the host to the vim on the virtual machine. Nothing. I opened pluma and could not copy to it. After all the updates and installs I rebooted and copy (from the host) to the VM worked as expected.
I have my CenOS host with 3 or 4 VMs running - a couple of dozen workspaces. I think my brain is loosing focus 
I will post back if I have any further experience to relate.
Thanks again,
Ken
Hello again Bill_MI,
I just built a Ubuntu Mate 18.04 virtual machine in VMWare to try and build and package gnome-commander. While installing a bunch of packages I found that Right Click disappeared from the Desktop. It worked on the panel and within a couple of open terminals and an open pluma window. Left click on the Desktop did not seem to do anything. Again I had to log out and back in to restore it.
Ken
p.s. Just happened again while installing a bunch of updates with the software updater (VM again, I hosed the previous one). After updater completed the Right Click function returned.
Hear yea, hear yea! I think I am on to something…
I just booted my Ubuntu Mate 18.04 virtual machine (VMWare)
I Right Clicked on the Desktop and opened a terminal
No more Rich Click response on the Desktop 
I closed the terminal - Right Click responds.
I opened my home in caja
No more Rich Click response on the Desktop
I closed the caja - Right Click responds (after Left Clicking on Desktop).
I opened my home and then a terminal from launcher on panel.
No more Rich Click response on the Desktop
I closed caja and bounced the mouse pointer against the left edge of the display a few times - Right Click responds again.
I currently have the terminal roughly centered on the monitor. Right Click works to the left of the terminal but not to the right.
Well I thought I had something - Right Click returns after closing one of the offending programs but it now does not seem that simple. Anyhow… I have documented what I ahve seen.
I have a UM 18.04 Clonezilla image for a physical machine. Let me restore that and see if this might be a VM related issue.
Ken
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Well so much for this… I have been experimenting on a physical machine. I cannot reproduce the issue. Looks like it might be related to VMWare Workstation/player.
I was about to write that I had figured out the problem but not the solution. I think I have found the solution but not the problem. I reinstalled UM 18.04 on VMWare Workstation/Player 12.5.9. The initial background is the green ubuntuMATE image. It fills the whole virtual machine window - which is not full screen on the monitor. I maximized the window and the Ubuntu image was tiled 2 and a fraction wide by 2 high. Right click would only work on the image in the upper right of the display.
I right clicked to Change Desktop Backgorund and observed that the display was not shown as tiled, rather it was “Zoom”. As I pondered this the image expanded to full screen. However, right click only worked where the original image had been in the upper right. I tried setting back to Tile but that makes the image expand. It is still one image and centered.
I dorked around for a while and basically, I was stuck with only the upper left of the desktop “alive.” I then un-maximized the window. The whole desktop in in the “windowed” window was alive to right click. I then stretched the window to almost full screen. The whole desktop was alive. I maximized the window.
The desktop is alive except for the small strip to the right and bottom where it expanded from its stretched size to maximized. I stretched the window as large as I could, maximized and then entered “full screen” mode - no window border around the VM. I see that the start of a second background image is overlapped at the bottom of the screen - about 10% of the screen height. This area is DEAD.
Apparently a conflict between Ubuntu’s management of the desktop size and VM Ware’s management of the display size. I don’t know if this makes sense. If not, please ask and I will try to clarify.
Ken
Is “Show Desktop Icons” enabled in MATE Tweak?
Yes - as installed/default. Home and Mounted Volumes are checked.
What Mickey said. I had the exact same problem. Turns out that when “show desktop icons” isn’t checked in appearance, the right click on desktop is deactivated for some reason
“show desktop icons” WAS checked, by default on this new install. To restate what I have found…
When I start the virtual machine it comes up in a window less than full monitor. If I maximize the window it appears that only the desktop area which was visible in the original window responds to a right click. If I stretch the window to fill the entire monitor then all of the desktop responds.
Ken
Final update (I hope). I upgraded VMWare workstation/player to version 14 and it seems that this phenomenon has gone away.
Ken
Final update? No 
It seems that I had moved the window containing the newly fired up VM to the upper left of the monitor and then maximized it. That seems to make the whole desktop active. If I maximize the window from where ever it starts… same original issue.
Ken
It seems that I had moved the window containing the newly fired up VM to the upper left of the monitor and then maximized it. That seems to make the whole desktop active. If I maximize the window from where ever it starts… same original issue.