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Controls Disappearing / Not Rendering intermittently

    Question

  • I have written a Windows RT 8.1 XAML/C# enterprise app which is installed on Lenovo Thinkpad 8 tablets.

    My users are experiencing a very intermittent issue where a number of controls on each screen would suddenly disappear or not render properly. It seems to be mostly controls along the top of the screen,

    For example on every screen there is a back button in the top left corner. This would be one of the controls that would disappear. However when you touch where the button should be then it still functions correctly.

    However the logo image which appears directly beside the back button still appears. There is then a textbox which appears to the right of it which will not be displayed.

    We can make these controls appear again by closing the app / suspending it and then opening it up again - sometimes you need to do this a couple of times.

    I cannot figure out why this would be happening.

    Various theories:

    • Some sort of problem with styling within the app - unlikely because it only affects a select number of controls on the screen and it is very intermittent.
    • graphics/rendering hardware issue
    • A memory problem relating to suspending and resuming the app

    Can anyone hazard a guess what might be happening?

    Thanks

    Thursday, December 11, 2014 3:26 PM

All replies

  • Hi Ryan,

    Do you have some reproducible demo for us to analysis?

    Generally speaking the app should not hide any controls in a sudden, if your back button is disappear probably your navigation history was cleaned, therefore the binding for back button visibility is become hidden, check some part of your code if you have programmatically remove the history.

    I don't think system will remove your current display items from the screen, the memory issue seems impossible, however graphic or rendering issue sounds more reasonable, I think we still need your sample for analysis.

    --James


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    Friday, December 12, 2014 9:26 AM
    Moderator
  • Hi James,

    Thanks for the reply - unfortunately we just cannot reproduce the problem and we have spent a lot of time trying.

    Also it is not just the back button that disappears. I have attached images to show how it looks before and after the problem. As I mentioned originally the buttons and links are still there and can be tapped but they are not rendered.
    Only when we suspend and reopen the app a couple of times do they re=appear. Changing the rotation of the device does not bring them back either.

    Thanks

    Friday, December 12, 2014 10:05 AM
  • Another example of a screen and the controls that do not render

    I should point out that the png logo image "Sysco" sometimes will stay on the screen and the other controls (back button, textblocks) all disappear.
    • Edited by Ryan Cairns Friday, December 12, 2014 10:29 AM
    Friday, December 12, 2014 10:06 AM
  • Thanks Ryan for your screenshots, I've never experienced with such issue.

    Anyway, could you validate when some controls are disappeared, their visibility are Visible. Is it possible some code programmatically hide your controls?

    Another possibility is as what you mentioned: graphics/rendering hardware issue. The suggestion for the code is to optimize the images by using small size and combine some UI elements as UerControl, also use less memory, we can hardly manage the hardware stuff.

    --James


    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
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    Monday, December 15, 2014 9:47 AM
    Moderator
  • Hi - I thought you might be interested that we may have gotten to the bottom of this problem. The culprit - Windows Accessibility Narrator. Narrator on these tablets is turned on by pressing the Windows button and the Volume Up button together and we suspect users are accidentally doing this.

    Narrator then seems to cause problems with my app including the previously mentioned missing controls - I witnessed this earlier.

    We are looking into having Narrator disabled on all the devices

    Wednesday, January 21, 2015 3:11 PM
  • Hi Ryan,

    Wow, Narrator, anyway, thanks for sharing the finding.

    --James


    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
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    Thursday, January 22, 2015 7:39 AM
    Moderator
  • Hi - unfortunately my "narrator theory" has been dis-proven.

    I left one of the devices charging for a very long period of time - the screen on the tablet does not switch off whilst charging. I had left it on the desktop screen.

    When I returned I witnessed the missing controls issue for the first time. As you can see in the video the controls in particular the back button are still functional even though they are not visible.
    And in one screen some of the controls appear for a second and then disappear.

    I can provide more details of what controls are missing but the back button is the most obvious one:
    https://onedrive.live.com/redir?resid=DF2BE823348DEA6C!67755&authkey=!AKnQzpLrcKHpp5g&ithint=video%2cmov


    Have you any ideas? Thanks

    EDIT UPDATE: I have just witnessed the problem a second time. The first time after I saw this I pressed the windows button to open the Start screen and then when I opened/resumed the app the missing controls re-appeared.

    However this time when I did that the controls re-appeared however now the logo (a 8kb png file) was missing from every screen.

    Could this image file be causing the problem somehow?

    • Edited by Ryan Cairns Friday, January 23, 2015 2:02 PM
    Friday, January 23, 2015 8:26 AM
  • Sorry to bump this but just wondering if anyone even had any theories on this? Even though there is a quick work around for this - click the windows key and open the app again, ,my customer is losing faith in the product and we are unsure as a software house whether the problem relates to our app, the hardware or the windows 8.1 RT platform.
    Friday, January 30, 2015 5:11 PM
  • Hi Ryan,

    I can see your video, thanks for that.

    However I would like to ask you to provide a reproducible demo for us to test *again*, because without the sample, I can hardly guess why the controls are hidden.

    And the way to narrow down the question is to go through the Visual tree to see if the hidden controls's visibility set to hidden, which can help us understand if this is a environment issue or the code issue.

    Thanks for your understanding.

    --James


    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
    Click HERE to participate the survey.

    Tuesday, February 03, 2015 7:26 AM
    Moderator
  • Hi,

    Unfortunately the problem is far from reproducible. If it was I might have figured out the problem by now based on the amount of time I have spent testing, tweaking things and testing again.

    In fact the problem seems to be specific to the hardware/tablet that we are using. It is extremely intermittent and only happens when the app is resumed from suspension.

    EDIT - deleted what I posted as my "latest theory" which was to do with resolution upscaling. The problem just occurred again for the first time in 3 days. At this stage I think I need to give up!

    Thanks

    Ryan


    • Edited by Ryan Cairns Monday, February 09, 2015 12:22 PM
    Monday, February 09, 2015 9:01 AM
  • Just a further update on this problem - still struggling to find an explanation:

    - The problem is not device/hardware specific. This is a huge breakthrough for me as it means it must be something specific to my app.

    - I tried changing the background of the app to a lighter colour to verify if the controls were actually disappearing or was there some sort of styling issue against the black background. Confirmed that they still disappear when using a white background.

    - I have implemented functionality to clear down the navigation page stack whenever the user returns to the home screen - this has made no difference.

    - I am now testing a version of the app without the png logo that you see in the video in the top left corner. It may be an hour/day/week before I see the issue again so I need to be patient!

    One thing to note with this logo is that sometimes when navigating between screens it may take a few seconds for it to appear on the screen. The png file is only 12kb.

    James you had mentioned about a UserControl to use less memory - I will try that next.

    Tuesday, February 24, 2015 2:36 PM
  • Hi - I have finally narrowed this problem down and created a very simple project which reproduces it.

    The problem is to do with images on pages - when I have images on my page and the app resumes they seem to cause other controls to disappear.

    As I have mentioned before in the live environment the problem is very intermittent however I have recently discovered that if I open an app, create a dump file this will force the same issue - this has been the only way I can reproduce the problem.

    If you see the video below this demonstrates it.
    https://onedrive.live.com/redir?resid=DF2BE823348DEA6C!74381&authkey=!AIvSU05r0363S3Y&ithint=video%2cMOV

    The project shown in the video can be downloaded below. Also I have tested this on two different tablet devices and with various image files - png and jpg.

    https://onedrive.live.com/redir?resid=DF2BE823348DEA6C!74382&authkey=!AIGHSdezFcCbEZQ&ithint=file%2czip

    Please can you investigate and advise how I should proceed.

    Thanks,

    Ryan

    Wednesday, February 25, 2015 12:45 PM
  • If it makes any difference the two tablets that I can easily re-create the problem on are both 32bit (Win 8.1, all latest updates installed).

    I am not able to confirm if the problem is specific to touch screens (driver problems?) or 32bit/64bit. But the steps to re-create are exactly the same on both.

    Thursday, February 26, 2015 10:12 AM
  • I have an issue that is happening intermittently but often with my live enterprise app. When a user would resume an app after being suspended textblocks would disappear on the screen.

    The issue appears to be caused by having image files on the page - if I remove all image files from my pages then the issue no longer occurs.

    Previously I was not able to recreate the issue but I would witness it happening intermittently on our test tables.

    Now I am able to force the issue by minimising the app, going to task manager and creating a dump file then resuming the app. If I do this a couple of times the issue occurs. Here is a video of the problem occurring:

    https://onedrive.live.com/redir?resid=DF2BE823348DEA6C!74381&authkey=!AIvSU05r0363S3Y&ithint=video%2cMOV

    So far I can re-create this problem on two different tablet devices both running Windows 8.1 Professional, 32bit edition. I do not currently have access to a tablet running 64 bit 8.1. Also I cannot re-create the problem on laptop running Windows 8.1 Enterprise, 64 bit.

    I have uploaded a test project to:

    https://onedrive.live.com/redir?resid=DF2BE823348DEA6C!74382&authkey=!AIGHSdezFcCbEZQ&ithint=file%2czip

    Also - I have tried using jpg, bmp and png files and the issue occurs with all of them.

    Finally this morning I have stripped down my code even further to

    <Page
        x:Class="TestImageProblem.MainPage"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:TestImageProblem"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
    
        <Grid >
            <Grid.ChildrenTransitions>
                <TransitionCollection>
                    <EntranceThemeTransition/>
                </TransitionCollection>
            </Grid.ChildrenTransitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="140"/>
                <RowDefinition Height="*"/>
            </Grid.RowDefinitions>
    
            <StackPanel Orientation="Vertical" Grid.Row="1">
                
                <Image Source="Images/Windows.bmp"
                    Grid.Column="1" Margin="0,10,10,10" 
                    HorizontalAlignment="Left" CacheMode="BitmapCache" Stretch="None"/>
                
                <TextBlock x:Name="Welcome" Text="Welcome Text" 
                           Grid.Row="0" VerticalAlignment="Top" FontSize="40" />
                
                <TextBlock x:Name="LoginMsg" Text="Login Message" 
                           Grid.Row="1" VerticalAlignment="Top" Margin="0,0,0,0" 
                           FontSize="52" />
            </StackPanel>
        </Grid>
    </Page>
    

    The problem still occurs.

    Any help would be extremely appreciated. I am willing to try any workarounds - worst case scenario I am going to have remove all images from all the pages in my apps.

    I am not sure why creating a dump file forces the issue - any thoughts here?

    Much thanks in advance.

    Friday, February 27, 2015 8:55 AM
  • Please open a support case for this issue.


    Matt Small - Microsoft Escalation Engineer - Forum Moderator
    If my reply answers your question, please mark this post as answered.

    NOTE: If I ask for code, please provide something that I can drop directly into a project and run (including XAML), or an actual application project. I'm trying to help a lot of people, so I don't have time to figure out weird snippets with undefined objects and unknown namespaces.


    Friday, February 27, 2015 7:26 PM
    Moderator