Overhead projected screen shows only wallpaper

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frisket
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Overhead projected screen shows only wallpaper

Post by frisket »

I took a new Dell XPS 15 into class today to use in teaching. It's running Cinnamon (no MS Windows), and has XFCE and Enlightenment as well. I plugged it into the projector cable, as I have done for years with a variety of other laptops old and new, using the Dell-supplier VGA connector, and the projector picked up the signal OK and displayed...the wallpaper. No icons, no applications, no dock, no shelf, no taskbar, and when I fired up Chromium, it started on the laptop screen but nothing appeared on the projected image. Very pretty wallpaper, but nothing else.

I logged out and switched to the other window managers in turn and got exactly the same results, so it appears to be independent of the WM. I'm not an expert in computer-to-projector connection except that experience shows that projectors are the worst-designed and most obtuse interfaces in existence :-) which is why I was pleasantly surprised that it even recognised the laptop.

But I have no clue why nothing else was visible: I thought the signal sent down a VGA output was a composite video-style signal, in effect a bitmap of the screen, so the projector needs no intelligence, and simply has to reproduce the coloured dots. Clearly I am missing something here, but I don't know what.
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all41
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Re: Overhead projected screen shows only wallpaper

Post by all41 »

Try this,
Navigate to settings for Display and enable Same image in all monitors
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AndyMH
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Re: Overhead projected screen shows only wallpaper

Post by AndyMH »

Alternatively, press fn + F7 (or it might be F8 - varies by laptop, look at the little blue icons on the function keys). This will then enable you to toggle between:
  • laptop or projector only
    laptop and projector (same screen)
    projector as an extension to laptop (which is what it sounds like you've got).
If you go for both showing the same screen you will only get the resolution of the lowest res device.
Thinkcentre M720Q - LM21.3 cinnamon, 4 x T430 - LM21.3 cinnamon, Homebrew desktop i5-8400+GTX1080 Cinnamon 19.0
frisket
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Re: Overhead projected screen shows only wallpaper

Post by frisket »

Thanks for the suggestions. Unfortunately ‘same in all monitors’ is already enabled, and pressing F8 had no effect.
rpbrown1952
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Re: Overhead projected screen shows only wallpaper

Post by rpbrown1952 »

Have you been able to solve this problem? I've had the exact same experience with two different laptops; a Dell E6500 Latitude and a Toshiba Satellite. The Dell has an INVIDIA graphics adapter , the Toshiba has Intel graphics. I've got Mint 18.3 installed on both and I get the same thing you do. Pretty wallpaper, no desktop. I'm a teacher and have converted my entire classroom to Linux with the exception of a Win10 machine that I am forced to use for all my lessons, lectures, etc because of this issue with Mint and projectors. Very frustrating & I wish someone could help us figure this one out. I've already tried the suggestions shown here, they don't work.
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Flemur
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Re: Overhead projected screen shows only wallpaper

Post by Flemur »

rpbrown1952 wrote: Fri Nov 16, 2018 11:51 am The Dell has an INVIDIA graphics adapter
See if you can fix that one with

Code: Select all

sudo nvidia-settings
You might have to install it.
Please edit your original post title to include [SOLVED] if/when it is solved!
Your data and OS are backed up....right?
Berk

Re: Overhead projected screen shows only wallpaper

Post by Berk »

I am having a similar problem with Mint 19.1 on a Toshiba L70D. I am running a dual boot alongside Win 7. My Epson projector does not recognize my VGA cable and selects USB. This is strange since when I boot Win 7, the same cable is recognized and display allows me to select mirror image or extended image.If I connect to the projecter with HDMI cable, I get a mirror image by default and it can't be changed. I installed the software for Nvidia on the Mint O/S so it should work. Something strange here. Any ideas anyone?

I'm stumped.
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himmatsingh

Re: Overhead projected screen shows only wallpaper

Post by himmatsingh »

Monitor settings are not correct. Even more, the problem seems to indicate that you can see the wallpaper in any projector according to that.
rpbrown1952
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Re: Overhead projected screen shows only wallpaper

Post by rpbrown1952 »

It's been a while since I came back here to see about this problem. But I have good news to share! I never did figure out how to get my laptops working with any projector while using Mint 18.3. That's the bad news. The good news is that when I upgraded to Mint 19.2 the problem went completely away and now both of these laptops work just great with my projectors.

So I'm guessing that the problem didnt have anything to do with the laptops and was just an inherent bug associated with Mint 18.X that was resolved in Mint 19.X
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Re: Overhead projected screen shows only wallpaper

Post by dexl »

Let me continue this happy thread with the sad one. Freshly installed LM20 displays pretty mint wallpaper on the projector (and nothing else). And trying to fix this in Displays, it turned off my laptop screen completely, nothing on the projector, I was forced to reboot to Windows. No problems there! It's funny that Linux Mint still has a display problem. Can it be fixed somehow?
Linux Mint 20 MATE
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shedyed
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Re: Overhead projected screen shows only wallpaper

Post by shedyed »

Those projectors still have that VGA in, I'm guessing. You are hooking it up to your laptop, and with that kind of setup your laptop screen will be the primary display; the projector is secondary, and has to be told what to display.

I am old school, and my thinkpads need their BIOS setup to inform the laptop what action to take when something is attached to VGA-out (laptop LCD only? external screen only? Or both?)

The command you are looking for is xrandr and xrandr -l lists all your output screens, if I recall correctly. Try that, or attaching the projector later, after boot, for example. xrandr can be used to output to both, and in different resolutions, as long as your HW can support it.

I know it's been a while; hope you found a solution easily.
mikeflan
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Re: Overhead projected screen shows only wallpaper

Post by mikeflan »

xrandr -l didn't work for me.
xrandr --verbose did work.

I am interesting in hearing how well LM 19.3 works with projectors. Old VGA projectors and new ones too. I suspect generally there is no problem. I need to buy one and welcome suggestions.
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