Hey,
We have a grid with editors per cell. on a few computers, at one point, the users are getting the following error:
System.NullReferenceException: Object reference not set to an instance of an object.
at Infragistics.Win.ValueListDropDownAppearanceManager.ResolveValueListItemAppearance(ValueListItemUIElement valueListItemElement, AppearanceData& appData, AppearancePropFlags requestedProps)
at Infragistics.Win.ValueListItemUIElement.InitAppearance(AppearanceData& appearance, AppearancePropFlags& requestedProps)
at Infragistics.Win.ValueListItemUIElement.PositionChildElements()
at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
at Infragistics.Win.UIElement.VerifyChildElements(Boolean recursive)
at Infragistics.Win.ControlUIElementBase.VerifyIfElementsChanged(Boolean verify, Boolean syncMouseEntered)
at Infragistics.Win.ControlUIElementBase.ProcessMouseHover(Object sender, EventArgs e)
at Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)
at Infragistics.Win.UltraControlBase.OnMouseHover(EventArgs e)
at System.Windows.Forms.Control.WndProc(Message& m)
at Infragistics.Win.ValueListDropDownUnsafe.WndProc(Message& message)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Thanks,
Mano
Hi Mano,
Thank you for contacting Infragistics Developer Support.
I will need more information about your scenario as I couldn’t reproduce the issue on my machine. What version of our controls are you using? What editors are you using? Are there appearance objects assigned to the editors? What were the users doing when they got the exception? Can you provide me with concrete steps to reproduce it?
Also it would be extremely helpful if you are able to isolate the issue in a small sample or at least provide code snipped.
I am looking forward to your response.
Thanks for your response.
We are using 13.2 but error also happened on old versions. I can't reproduce it on my computer. just on a very few computers. We have a few cells with a EditorWithCombo applied to. At one point when the user click to open the drop down, the error appeared.
Sorry, I can't replicate it,
Without a sample or a lot more information, all I can do is take some really wild guesses here.
Is your application using threading? Are you creating any background threads? That might cause a problem like this.
Also, it is possible that you are using the same Editor or EditorControl for more than one grid? It's generally not a good practice to use a single editor in more than one control, although you can use the same one for more than one column or cell within the same grid.
What event(s) are you using to assign the editor to the cell(s)?
Are you handling other events that might be related to dropping down the list, like BeforeCellListDropDown or the DropDown event of the editor?
Are you populating the combo dynamically while the app is running, or just once up-front?
We found that this issue related to the HARDWARE (Panasonic CF-19) that our customers are using. This is why we can't replicate the issue. Here is the latest information that we have to describe the issue:
When the Panasonic CF-19 is in "laptop mode" we see no issues. When the screen is rotated and locked, the device goes into "tablet" mode with an onscreen keyboard. In this mode, we receive the reported error when entering into edit mode. The error is coming form a cell with EditorWithCombo, but it can happened even when entering into edit mode on other calls.
I hope additional information helps.
Thank you very much for your co-operation, it is really appreciated. Please let me know the results as soon as you have tested the sample.
I am looking forward to your reply.
Thanks!. We are going to test it and let you know what we find ASAP.
We tried to reproduce this issue using Windows surface device under Windows 8.1 Pro with screen resolution 1920 x 1080 (Landscape) and 1080 x1920 (Portrait). Everything worked properly, no exception was thrown. Please check the attached sample and let us know if you can reproduce the issue with it. If you can’t, please modify the sample. If we have a sample that exhibits the issue we will try to find device on which we could reproduce it.
Well, I don't have that particular piece of hardware to test with. So I'm not sure what other assistance I can offer you there.
My guess is that the issue probably isn't hardware-specific. It's more likely that something about that situation is causing the error. Like maybe it's the particular screen resolution or the position of the grid / keyboard on the screen.
Maybe you could try to duplicate the same situation on another machine with the specific hardware and see if you can get the exception to occur that way.
Another screenshot.
Thanks!