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I am working on a WPF main window and I am using a list box, and I want the list box to auto-scroll whenever new data is added. I used the ListBoxBehavior class in the chosen answer for this question, and I added the following namespaces for the that class in my code:

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;

Also, in my XAML, I added the following:

<ListBox x:Name="IncomingData" FontSize="20" Grid.Column="1" Margin="10,10,10,0" Grid.Row="3" ItemsSource="{Binding SourceCollection}" lb:ListBoxBehavior.ScrollOnNewItem="true"/>

However, I am getting the following three errors in my XAML code regarding that line, and they are as following:

  1. Error XDG0006 The namespace prefix "lb" is not defined.
  2. Error XDG0008 ListBoxBehavior is not supported in a Windows Presentation Foundation (WPF) project.
  3. Error XLS0415 The attachable property 'ScrollOnNewItem' was not found in type 'ListBoxBehavior'.

I tried creating an object of a ListBox type ListBox lb = new ListBox(); in the ListBoxBehavior class, but that didn't change the situation. Also, ScrollOnNewItem already exists in the class, so why is it not identifying it? Is there a missing step that I should have done? Any help is much appreciated!

Archeologist
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1 Answers1

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you need to define the lb namespace before using it.

at the top of your xaml file you ought to see xmlns:x="...". notice you are using it with x:Name.

same goes for lb. you need to define xmlns:lb="...". intellisense should help you fill in the "...".

notice xmlns means xml namespace.

that ought to clear up all 3 errors.

Kirk Horton
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  • Thank you! I tried this and I set the namespace for lb to be as follows: ```xmlns:lb="DataViewer.ListBoxBehavior"``` such that DataViewer is the namespace that has the class ListBoxBehavior, MainWindow.xaml, and the code behind it in C#. However, that cleared only the first error regarding the prefix, and the other two are still there. Is it wrong howI defined the namespace, or should I define it in another way? – Archeologist Feb 04 '20 at 17:27
  • the type is ListBoxBehavior, and it is a member of the namespace DataViewer, so it's rather like `xmlns:dv="DataViewer"` which you'd then reference the behavior like `dv:ListBoxBehavior.ScrollOnNewItem="true"`. i guess the format's like `namespace:Type.Property="value"` – Kirk Horton Feb 04 '20 at 19:10
  • Now all errors have been fixed except a new one that appeared after I declared the namespace ```xmlns:lb="DataViewer"``` which visual studio has automatically set it to ```xmlns:lb="clr-namespace:DataViewer"``` The error is the following: The name "ListBoxBehavior" does not exist in the namespace "clr-namespace:DataViewer" I think the issue here is that Visual Studui isn't recognizing the ListBoxBehavior class within the namespace. It was already set to Compile when I checked the Configuration Manager. However, thanks a lot for your help. – Archeologist Feb 06 '20 at 16:26