Images of previously opened windows & apps appear when I change desktops

[Ronshere]

Hi
What's happening is images of the windows and apps I have had opened appear during the interval that it takes for the desktops to change as I click through them.
In other words, each time I switch to a different desktop I can see images flash on the monitor of apps that I had opened, some of them are even of the logiin screen.
For instance, I login and open firefox. Then I decide to switch to a different desktop. I can see a popup showing me Firefox is open on another desktop as well as other images of apps that I might have used but have closed. They just seem to be phantom images that appear in between the desktops as they switch.
This is my third fresh install of the latest Kubuntu and it has happened each time. I can't resolve it, don't even know where to start.
I have attached a screen shot of what I see. It does change however as time goes on but this is typical. Note that this saying I am updating but that was a while before and the task completed and I had closed the updates.

[SteveRiley]

Re: Images of previously opened windows & apps appear when I change desktops

You know, I've seen the same thing lately. What graphics card, driver, and driver version are you using?

[Ronshere]

Re: Images of previously opened windows & apps appear when I change desktops

Hi
Thanks for replying. I am using an Nvidia 7300GT card.
As for the driver it is whatever is initially installed with Kubuntu 11.10.
I did however run a perfunctory driver update upon each install so
the default drivers may have updated. But the problem existed
before and after the updating.
I am glad you understood me and have seen this trouble. I wasn't sure if
I was able to explain it correctly!
BTW I had a Radeon 5670 in my box but gave it to my wife.
The trouble happened with that as well.

[SteveRiley]

Re: Images of previously opened windows & apps appear when I change desktops

Mine's an nVidia 3100M using version 290.10 of the proprietary driver.

Hey Kubuntu-land... anyone else out there seeing the behavior that Ronshere and I have noticed?

[dibl]

Re: Images of previously opened windows & apps appear when I change desktops

Hey Kubuntu-land... anyone else out there seeing the behavior that Ronshere and I have noticed?

I did used to see that, with an Nvidia 7900-GS card. IIRC, my google-fu eventually revealed that it is caused by cached graphics memory being accessed, or leaked, during a subsequent video memory access. The cached imagery even survived warm reboots -- when I was dual booting Kubuntu and Debian, it would be very strange to catch a brief glimpse of the other OS's splash screen after a reboot. Although disconcerting, it does not indicate anything bad going on.

[Ronshere]

Re: Images of previously opened windows & apps appear when I change desktops

Hi
Where would this be cached? I have cleaned everything I could find but it still happens. Is it possible to edit the instructions to prevent caching or stop it being read?
Anyway, I think anything disconcerting is bad as it is a nuisance and distraction. In this case it annoyingly throws me off as I switch windows. Besides, its an obvious error in the coding that needs attention.

[dibl]

Re: Images of previously opened windows & apps appear when I change desktops

Your video card has onboard graphics memory, which is used by the GPU -- you can't purge it by any user command. That's where the imagery gets cached.

[Ronshere]

Re: Images of previously opened windows & apps appear when I change desktops

Hi
Thanks for the info! Sounds like a driver trouble then. But my Radeon had the same problem?? The mystery deepens

I just remembered I have onboard video so I just now switched to it. Its Radeon 4250HD built into my mobo. It does not happen now! I figured the mobo would clear the ram cache and that seems to be working. I suspect this is a Kubuntu thing as it does not happen with pclinuxos or mint kde and a few other distros.
I have noticed something else. Now the desktop cube animation does not work. No changes except the video card swap I mentioned.
I tried just unchecking and rechecking the cube animation effect to reapply it and see if it works but a popup appears telling me that the following effects will not be applied, blur, desktop cube animation etc.
This is the same popup that appears when I ran the Live DVD and tried to apply the desktop cube animation!

[SteveRiley]

Re: Images of previously opened windows & apps appear when I change desktops

I have noticed something else. Now the desktop cube animation does not work. No changes except the video card swap I mentioned.
I tried just unchecking and rechecking the cube animation effect to reapply it and see if it works but a popup appears telling me that the following effects will not be applied, blur, desktop cube animation etc.
This is the same popup that appears when I ran the Live DVD and tried to apply the desktop cube animation!

Have you tried System Settings | Desktop Effects | Advanced and placing a check next to Disable functionality checks?

[Ronshere]

Re: Images of previously opened windows & apps appear when I change desktops

Have you tried System Settings | Desktop Effects | Advanced and placing a check next to Disable functionality checks?

Hello
your suggestion has cleared up the problem, however, I have to say it only fixed a part of it.
By that I mean I found something else that was also part of the trouble.

I had been using the 7300gt card and the trouble existed then. However, as i mentioned I switched over to my onboard video and the trouble persisted. But Dibl reminded me that the video ram was caching the images. I rechecked everything and realized that i had left the 7300gt plugged in even though I was using the onboard. I thought about this and had an idea. Dibl kicked my brain into gear! I reinstalled Kubuntu with the 7300 still plugged in but using the onboard video enabled in my bios and the 7300gt disabled!!.
During the installation I saw that Kubuntu was installing Nvidia drivers rather than the ATI drivers for the radeon 4250!!
The same trouble occured again!
I am fairly certain this is the main cause of the trouble! Kubuntu was caching in the 7300gt even though it was not being used as well as the onboard ram cache! its an interesting bug.
So I did another hard drive erasure and reinstalled Kubuntu again without the 7300 plugged in.
This made a big difference for the better but not completely. Certain images still lingered, particulary they were the drop down menus when I tinkered with the desktop animation settings. The other images no longer showed. However, when I applied your suggestion it has cleared up completely!! Many thanks for that!
There has to be a bug in the video caching which starts during installation.
I am used to leaving an unused video card in with windows with no problems about the caching (I switch back and forth when doing intensive graphics) but Kubuntu picked it up apparently as an active device and tried to use it as well as the onboard video! However, there is still some caching bug that shows even without the 7300gt and your suggestion fixed that!
I hope someone can figure out the fix to this.